Self powered module integrity indicator using piezoelectric sensor

Abstract

To provide a preferable device.SOLUTION: A device for monitoring the integrity of a membrane module. The device has a piezoelectric sensor capable of generating a voltage when exposed to vibrations and a light emitting diode electrically connected to the piezoelectric sensor, the piezoelectric sensor and the visual indicator being located sufficiently close to the membrane module to sense a vibration.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Hollow fiber or other membrane water treatment devices utilize methods to determine whether the fibers or membranes are intact or defect-free. These methods can include a bubble point test, in which air is used to force water through the pores of the membrane. The air pressure required can be correlated to pore size. Another method is a pressure decay test. [Background technology]

[0002] Pressure Decay Test (PDT) The pressure decay test (or pressure retention test) is the most common test method used in the field and is performed in situ below the bubble point by reversing the permeate flow with pressurized air. When all the water that filled the membrane lumen permeates back through the membrane, the membrane lumen is filled with pressurized air. Because of capillary suction pressure, air cannot escape from the membrane as long as the pressure is below the bubble point. After isolating the membrane from the pressure source, the lumen pressure is monitored for a predetermined period of time (usually 5 to 20 minutes). If there are defects on the membrane surface, air can permeate through the defects, causing a rapid drop in pressure. If there are no defects, the amount of air lost by diffusion through the membrane pores is negligible.

[0003] However, it is not entirely clear where to draw the line between normal and abnormal pressure decay rates. Summary of the Invention [Problem to be solved by the invention]

[0004] The pressure decay test is particularly useful for hollow fiber membranes with an integral skin and support layer. It can also be used for hollow fiber membranes and flat sheet membranes without an integral skin layer, although the maximum allowable air pressure may not be high enough to detect defects smaller than, for example, 3-5 microns.

[0005] Variations on the pressure decay test include the use of a microphone or noise sensor, which is used to detect air escaping from defective fibers. The current method of module integrity check is to use a sonic analyzer, or microphone, to "observe" and evaluate the noise level within the module. However, using a microphone requires a power source, which may not be readily available. [Means for solving the problem]

[0006] In one embodiment, piezoelectric elements can generate electricity from deformation or vibration, and vice versa. These circuits are well known. DETAILED DESCRIPTION OF THE INVENTION

[0007] This circuit can be a box, perhaps no larger than 50mm x 50mm x 10mm, that can be attached to the housing of a pressurized hollow fiber module. When PDT is performed and the module is not perfect, i.e., if there are leaky fibers, a lot of noise (vibration) will be generated. This vibration is then converted into an electrical signal that can be used to power a visual signal, such as a light-emitting diode (LED).

[0008] The proposed method is to provide a visual indicator (via a change in brightness or color) that is linked to the noise level. The amount of power generated is proportional to the amount of noise emitted from each module. Therefore, the LED indicator can change color or intensity depending on the noise level from the module. This provides a visual indication of the relative integrity of each module. A higher amount of noise means a larger voltage is generated, and therefore the LED will light up brighter compared to when the noise output from the module is low.

[0009] The entire piezoelectric assembly can also be fabricated on a circuit board or integrated circuit, further reducing their size and cost when mass produced.

[0010] The main advantage of the proposed indicator is that it saves time for customers during troubleshooting: the relative noise level of each module can be viewed from a distance, compared to the sonic analyzer method, which requires physical access to each module.

[0011] The phraseology and terminology used herein are for purposes of description and should not be considered limiting. As used herein, the term "plurality" refers to two or more items or components. The terms "comprising," "including," "carrying," "having," "containing," and "involving," whether in the written description or claims, are open-ended terms, i.e., mean "including, but not limited to." Thus, the use of such terms is meant to encompass the items recited by that term, and equivalents thereof, as well as additional items. With respect to the claims, only the transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases, respectively. The use of ordinal terms such as "first," "second," "third," etc. to modify claim elements in a claim does not, by itself, imply any priority, precedence, or order of one claim element relative to another or the temporal order in which the actions of a method are performed, but is merely used as a label to distinguish one claim element having a particular name from another element having the same name (absent the use of ordinal terms), thereby distinguishing the claim elements.

Claims

[Claim 1] 1. An apparatus for monitoring the integrity of a membrane module, comprising: a piezoelectric sensor capable of generating a voltage when exposed to vibration; and a visual indicator comprising a light-emitting diode electrically connected to the piezoelectric sensor, wherein the piezoelectric sensor and the visual indicator are positioned sufficiently close to the membrane module to sense vibration.