US 6,161,435 A · Method and apparatus for determining the state of fouling/cleaning of membrane modules

Abstract

The fouling state of a polymeric membrane within the high pressure housing of a spiral wound or a hollow fiber membrane module is determined. An ultra sonic transducer positioned with its emitting face in physical engagement with the outer surface of the housing is pulse energized by a pulser/receiver device. A membrane echo signal is detected by a receiver of the pulser/receiver device. A reference echo signal indicative of a fouled or an unfouled state of the membrane is compared to the echo signal to determine the membrane fouling state. The echo to reference comparing step can be based upon comparing amplitude domain signals, comparing time-domain signals, comparing combinations of amplitude domain and time-domain signals, and comparing transformations of amplitude domain and time-domain signals. A clean or a fouled reference echo can be provided from a clean or a fouled membrane and then stored for use during a liquid separation process, or a clean reference echo signal can be obtained on-line from a second transducer whose echo signal is derived from an area of the membrane known to remain relatively unfouled during the liquid separation process, or a clean or fouled reference echo signal can be provided for later use during a cleaning process or during a liquid separation process. Multiple transducers and a switching network can sample the fouling state at different positions within the membrane module.

Claims50

Dependent claims

A method of monitoring a state of fouling of a membrane that is contained within a housing of a spiral wound or a hollow fiber membrane module, said housing having an outer surface, comprising the steps of:

providing an ultrasonic transducer having an emitting face;
positioning said transducer with said emitting face in physical engagement with said outer surface;
pulse energizing said transducer;
detecting a membrane echo signal that results from said pulse energization of said transducer;
providing a reference echo signal that is indicative of an unfouled state of said membrane or of a fouled state of said membrane;
comparing said membrane echo signal to said reference echo signal;
and
determining said state of fouling of said membrane based upon said comparing step.

5 more elements

A method of monitoring a cleaning process by which a fouled membrane is cleaned, the membrane being selected from the group hollow fiber membrane and spiral-wound membrane, and said membrane being contained within a housing having an outer surface, comprising the steps of:

providing an ultrasonic transducer having a face surface;
positioning said transducer on said outer surface with said face surface in physical engagement with said outer surface;
starting said cleaning process;
pulse energizing said transducer;
detecting a membrane echo signal that is produced by said pulse energization of said transducer;
providing a reference echo signal that is indicative of a clean state of said membrane, or alternatively providing a reference echo signal that is indicative of a fouled state of said membrane;
comparing said membrane echo signal to said a reference echo signal;
determining a state of cleaning of said membrane based upon said comparing step;
and
terminating said cleaning process as a function of said determining step.

7 more elements

A met hod of monitoring a state of fouling of membranes in a multi-layer configuration, comprising the steps of:

providing a membrane module having a housing with an outer surface, having said multi-layer membrane configuration contained within said housing, having a feed inlet, having a permeate outlet, and having a retentate outlet;
providing a first and a second ultrasonic transducer, each of said transducers having a face surface that generally corresponds to said outer surface of said housing;
positioning said first transducer on said outer surface of said housing general adjacent to said feed inlet and with said face surface in physical engagement with said outer surface;
positioning said second transducer on said outer surface of said housing general adjacent to said retentate outlet and with said face surface in physical engagement with said outer surface;
pulse energizing said first and second transducers;
detecting a first and a second membrane echo signal that are respectively produced by said pulse energization of said first and second transducers;
said first membrane echo signal being indicative of membrane fouling generally adjacent to said feed inlet;
said second membrane echo signal being indicative of membrane fouling generally adjacent to said retentate outlet;
comparing said first membrane echo signal to said second membrane echo signal;
and
determining said state of fouling of said multi-layer membrane configuration based upon said comparing step.

8 more elements

Apparatus for determining the state of fouling of a liquid separation membrane that is contained within a housing having an outer surface, having a liquid feed inlet, having a permeate liquid outlet that is physically spaced from said liquid feed inlet by said membrane, and having a retentate liquid outlet that is physically spaced from said liquid feed inlet and generally comprises an extension of said liquid feed inlet, said apparatus comprising:

at least one sensing ultrasonic transducer mounted on said housing generally adjacent to said permeate liquid outlet, said at least one transducer having a wave energy emitting/receiving face surface whose shape physically complements said outer surface of said housing;
sensing pulser/receiver means connected to said at least one transducer and operable to cause said at least one transducer to operate in a pulse/echo mode of operation wherein for each pulse energization of said at least one transducer by a pulse portion of said sensing pulser/receiver means a wave of energy is transmitted through said housing and into said membrane, and an echo wave of energy is thereafter received by said at least one transducer, said echo wave of energy being converted to an electrical signal by said at least one transducer, and said electrical signal then being processed by a receiver portion of said sensing pulser/receiver means;
an electrical source providing a reference signal indicative of a reference state of fouling of said membrane;
comparison means having a first input connected to receive said processed electrical signal from said receiver portion of said sensing pulser/receiver means, having a second input connected to receive said reference signal, and having an output;
a threshold signal source operable with said comparison means and defining a predetermined state of fouling of said membrane;
such that when said apparatus is used to monitor a state of fouling of
said membrane module as a liquid is being separated, said output provides a signal indicative of a need to clean said membrane module;
and
such that when said apparatus is used to monitor a state of fouling of said membrane module as said membrane module is being cleaned, said output provides a signal indicative of termination of said membrane module cleaning.

6 more elements

A method that determines fouling of a membrane utilized for liquid separation and that is contained within a housing having an outer surface, having a liquid feed inlet, having a permeate outlet that is physically spaced from said liquid feed inlet by said membrane, and having a retentate outlet that is physically spaced from said liquid feed inlet and is generally an extension of said liquid feed inlet, said method comprising the steps of:

providing at least one sensing ultrasonic transducer that is mounted on said outer surface of said housing generally adjacent to said retentate outlet, said at least one sensing transducer having a wave energy emitting/receiving face surface whose shape complements said outer surface of said housing;
providing sensing pulser/receiver means connected to said at least one sensing transducer and operable to cause said at least one sensing transducer to operate in a pulse/echo mode wherein for each pulse energization of said at least one sensing transducer by a pulse portion of said sensing pulser/receiver means a wave of energy is transmitted through said housing and into said membrane, and to cause an echo wave of energy to be thereafter received by said at least one sensing transducer, said echo wave of energy being converted to an electrical signal by said at least one sensing transducer, and said electrical signal then being processed by a receiver portion of said sensing pulser/receiver means;
providing an electrical source that provides a reference signal indicative of a reference state of fouling of said membrane;
providing comparison means having a first input connected to receive said processed electrical signal from said receiver portion of said sensing pulser/receiver means, having a second input connected to receive said reference signal, and having an output;
such that when said method is used to monitor a state of fouling of said membrane module as a feed liquid is being separated, said output provides a signal indicative of a need to clean said membrane module;
and
such that when said method is used to monitor a state of fouling of said membrane module as said membrane module is being cleaned, said output provides a signal indicative of the fact that said membrane module is clean.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for determining the state of fouling/cleaning of membrane modules

Life of this patent

Method and apparatus for determining the state of fouling/cleaning of membrane modules

Life of this patent

Abstract

Claims50