AU2016201216B2

AU2016201216B2 - Glycol sensor for feedback loop control

Info

Publication number: AU2016201216B2
Application number: AU2016201216A
Authority: AU
Inventors: Craig Kelly
Original assignee: Prolitec Inc
Current assignee: Prolitec Inc
Priority date: 2010-10-22
Filing date: 2016-02-26
Publication date: 2017-02-09
Anticipated expiration: 2031-10-24
Also published as: AU2016201216A1; AU2011338964A1; EP2629808A1; EP2629808A4; CN103402555A; WO2012078250A8; HK1191577A1; WO2012078250A1; CN103402555B

Abstract

Abstract A method of maintaining a desired level of an aerosolized compound within a space to be treated with the compound, the method including providing a diffusion device with the compound in liquid form and a control system for operating the device. The control system includes a sensor in fluid communication with the air within the space to be treated configured to sense the concentration of the compound aerosolized within the space. The diffusion device is operated to diffuse the compound into the space. The concentration of the compound within the space to be treated is sensed with the sensor and operation of the diffusion device is altered based on the concentration of the compound sensed to achieve a desired concentration of compound within the space. The sensing and operation altering steps are repeated periodically to maintain the desired concentration of the compound within the space. 7000595_1

Description

GLYCOL SENSOR FOR FEEDBACK LOOP CONTROL 2016201216 26 Feb 2016

Cross-reference to Related Applications

The present application is a divisional application of Australian Patent Application No. 2011338964, the disclosure of which is incorporated herein by reference. Australian Patent Application No. 2011338964 is derived from PCT Patent Application No. PCT/US2011/057550, filed on 24 October 2011. PCT Patent Application No. PCT/US2011/057550 claims priority to U.S. Provisional Application Serial No. 61/405952, filed on 22 October 2010, and U.S. Patent Application No. 13/090240, filed on 19 April 2011. U.S. Patent Application No. 13/090240 is a continuation-in-part application of U.S. Patent Application Serial No. 11/691363, now issued as U.S. Patent No. 7,930,068.

Background of Invention

The inactivation of airborne microorganisms as a method of inhibiting the transmission of disease can be achieved through the use of airborne air sanitizers, air disinfectants, and air sterilizers (hereafter disinfectants). Diffusion controlled encounters between airborne microorganisms and disinfectants serves as a basis for inactivation of the microorganism by mechanisms that are microorganism and disinfectant specific.

As a result of the requirement for diffusion controlled encounters between the airborne microorganism and disinfectants, a necessary step in the microorganism inactivation process, the rate of microorganism inactivation by the disinfectant is dependent upon the rate of the microorganism-disinfectant encounters. The rate of the encounters can be represented as a second-order kinetic process. The rate of a second-order event can be defined as a function of the airborne concentrations of the two reacting components, the microorganism and the disinfectant. The airborne concentration of the disinfectant is therefore an important parameter 1 2 2016201216 16 Jan 2017 controlling the rate of airborne microorganism inactivation by airborne disinfectant and therefore the control of the airborne concentration of the disinfectant is critical for any air disinfection process.

Summary

According to one aspect of the present disclosure, there is provided a method of maintaining a desired level of an aerosolized compound within a space to be treated with the compound, the method comprising: providing a diffusion device including the compound to be aerolosized in liquid form and including a control system for operating the device to diffuse the compound into the air within the space to be treated; providing the control system of the diffusion device includes a sensor in fluid communication with the air within the space to be treated, the sensor configured to sense the concentration of the compound aerosolized within the space to be treated; operating the diffusion device to diffuse the compound into the space to be treated; sensing the concentration of the compound within the space to be treated with the sensor and altering the operation of the diffusion device based on the concentration of the compound sensed within the space if necessary to achieve a desired concentration of compound within the space to be treated; and repeating the sensing and altering step periodically to maintain the desired concentration of the compound within the space to be treated.

According to one aspect of the present disclosure, there is provided a liquid diffusion device for treating a space with a liquid compound, the liquid diffusion device comprising: a control system for operating the liquid diffusion device to diffuse the compound into the space to be treated; the control system including a sensor in fluid communication with the air in the space to be treated, the sensor configured to sense the concentration of the compound within the air of the space to be treated; and the control system configured to alter the operation of the liquid diffusion device based on the concentration of compound sensed within the space to be treated and a desired concentration of that compound.

According to another aspect, there is provided a method of maintaining a desired level of an aerosolized compound within a space to be treated with the compound, the method comprising: providing a diffusion device including the compound to be aerolosized in liquid form and including a control system for operating the device to diffuse the compound into the air within the space to be treated;

AH26(11931398_1):CYL 2a 2016201216 16 Jan 2017 providing the control system of the diffusion device with a sensor in fluid communication with the air within the space to be treated, the sensor configured to sense the concentration of the compound aerosolized within the space to be treated; operating the diffusion device to diffuse the compound into the space to be treated; sensing the concentration of the compound within the space to be treated with the sensor and altering the operation of the diffusion device based on the concentration of the compound sensed within the space if necessary to achieve a desired concentration of compound within the space to be treated; providing a photoionization detection device operable to ionize the compound to be diffused into the space and to sense the ionization potential thereof; and repeating the sensing and altering step periodically to maintain the desired concentration of the compound within the space to be treated.

According to another aspect, there is provided a liquid diffusion device for treating a space with a liquid compound, the liquid diffusion device comprising: a control system for operating the liquid diffusion device to diffuse the compound into the space to be treated; the control system including a sensor in fluid communication with the air in the space to be treated, the sensor configured to sense the concentration of the compound within the air of the space to be treated; and the control system configured to alter the operation of the liquid diffusion device based on the concentration of compound sensed within the space to be treated and a desired concentration of that compound; the device further comprising a photoionization detection device operable to ionize the compound to be diffused into the space and to sense the ionization potential thereof.

According to another aspect, there is provided a compound diffusion device for treating a space, comprising a control system; a diffusing means operatively controlled by the control system to aerosolize a compound into the space; a sensor controller by the control system to detect a concentration level of the aerosolized compound in the space; and

AH26(11931398_1):CYL 2b 2016201216 16 Jan 2017 a photoionizer controlled by the control system to ionize the aerosolized compound and to detect an ionization potential thereof, wherein the control system is operable to control operation of the diffusing means and the photoionizer based on the detected concentration level and the detected ionization potential of the aerosolized compound in the space, wherein the photoionizer is operable to ionize the aerosolized compound with an ionization potential of not greater than or equal to 9.6 eV.

AH26(11931398_1):CYL 2016201216 26 Feb 2016 sensor feed-back loop, the output of glycol from the aerosol generator can only be controlled through indirect methods, e.g., through duty cycle, timed program, or manual on/off mechanisms while environmental variables can dramatically and dynamically alter the airborne concentration of gaseous glycol. Such approaches to control of glycol output are described in commonly owned U.S. Patent Application Serial No. 11/691363, now issued as U.S. Patent No. 7,930,068, the disclosure of which is incorporated herein by reference.

The present disclosure is directed to the development and incorporation of a sensor that is capable of detecting and monitoring the concentration of gas phase glycol into the operation of a airborne disinfectant diffusion device. If a reliable sensor can be identified than it can be integrated into a suitable control system to enable inhibition or excitation of the aerosol generator output in a manner that would allow the maintenance of a predetermined concentration of glycol vapor within a space to be treated. This would permit efficiency of operation of the device where the appropriate effective concentration is maintained for the desired efficacy without the distribution of an excess amount of disinfectant that may precipitate ontop surfaces in the treated space and possibly be wasteful of the disinfectant.

It is not intended to limit the present disclosure to any particular device for emitting or aerosolizing a glycol or other airborne disinfectant. Whatever method or device is used to distribute the airborne disinfectant through a space to be treated, the concentration of the disinfectant present in the space is to be measured and the concentration of disinfectant measured can be used to drive the operation of the device or method to distribute more or less disinfectant into the space. 3 2016201216 26 Feb 2016

Photoionization detection (PID) detectors were identified which had the capability to photoionize molecules with ionization potentials < 10.6 eV is an effective method of detecting and monitoring the gas-phase concentration of glycol in the treated space. For verification of the detection capability, a comparison was made against a known device, namely a Baseline®-mocon®, inc. VOC-TRAQ USB Toxic Gas Detector and Data Logger using a Silver piD-TECH® plus 0.02-20 ppm dynamic range (isobutylene) sensor.

Figure 1 provides experimental verification of the ability to detect propylene glycol, isopropyl alcohol, and triethylene glycol by the PID sensor or detector when the PDI detector is exposed to high concentrations of the respective vapors. The figure also provides an indication of baseline noise/variability in an uncontrolled interior environment.

Propylene glycol gas-phase concentration was studied under uncontrolled ventilation rate conditions as a function of aerosol generation rate, Figure 2. In addition to increased sensor readings that correlate with increased aerosol generation rate, low-frequency oscillations are observed that correlate with HVAC activity (air conditioning) and high-frequency oscillations that correlate with room entry/exit activity. When integration is completed, the sensor readings may be used to control the aerosol generation rate to compensate for the baseline variability associated with ventilation rate variability (e.g., HVAC and room entry/exit activity). Additional sensors could be provided in the control system for the operation of the disinfectant diffusion device to respond to such events before the events have an adverse impact on the concentration disinfectant in the space. By way of a non-limiting example, the control system may include a door sensor that would trigger a reaction by the diffusion system 4 2016201216 26 Feb 2016 when an entry ot exit is recorded. Alternatively, the control system may include a detector indicating when the HVAC system feeding the treated space is activated and the nature of the HVAC system’s operation (heating, cooling, venting, air or heat exchange, etc.).

It is anticipated that a photoionization detector that is capable of ionizing molecules with ionization potentials of < 9.6 eV may also be used within the scope of the present disclosure. The photoionization potential of triethylene glycol is approximately 9.6 eV and the ionization potential of propylene glycol is assumed to be similar to that for triethylene glycol or approximately 9.6 eV. If detection at < 9.6 eV is as sensitive for glycol detection as at < 10.6 eV, the lower ionization potential detector may provide improved selectivity for the glycols by virtue of not detecting potentially interfering molecules greater than about 9.6 eV, thereby eliminating potential contribution to the sensor noise from ionizable volatile organic compounds with ionization potentials in the 9.6 - 10.6 eV range which are not the desired disinfectant compounds. If the < 9.6 eV detector is unable to detect the glycols, or the sensitivity is greatly reduced, use of a dual detector may be developed to subtract out the < 9.6 eV signal to improve the selectivity for the detection of the glycols by virtue of removing potentially interfering signals from easily ionizable volatile organic compounds. Selectivity toward the glycols is therefore expected by one of the two strategies, with success of each dependent upon the precise ionization potential of the glycols and the efficiency of ionization of the glycols by each of the two detectors. Selectivity is potentially of value under conditions of interfering, non-glycol, volatile organic compounds. 5 2016201216 26 Feb 2016

Upon finalization of the sensor configuration, as described above, the sensor may be integrated into the any sort of aerosol generators to enable a feed-back control mechanism facilitating automatic aerosolization rate control for maintenance of a predefined glycol gas-phase concentration. That is, the sensor will serve a function that is comparable to a thermostat for temperature control, except it will maintain the glycol, rather than the heat, level. Such sensor configurations may be used to control operation of a number of different devices that may operate to distribute or diffuse disinfectant within a space to be treated.

It is anticipated that the sensing, analysis and detection of glycols compounds as described herein may be extended to other aerosol organic compounds as well. It is anticipated that similar analysis and evaluation of data received from sensor(s) positioned within a particular space may be used to determine the presence of other airborne organic compounds and also to identify potentially unknown compounds. It is not the intention of limit the present disclosure to solely the identification and evaluation of glycols or to any particular disinfectant compounds.

While the invention has been described with reference to preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Thus, it is recognized that those skilled in the art will appreciate that certain substitutions, alterations, modifications, and omissions may be made without departing from the spirit or intent of the invention. Accordingly, the foregoing description is meant to be exemplary only, the invention is to be taken as including all reasonable equivalents to the subject matter of the invention, and should not limit the scope of the invention set forth in the following claims. 6

Claims

1. A method of maintaining a desired level of an aerosolized compound within a space to be treated with the compound, the method comprising: providing a diffusion device including the compound to be aerolosized in liquid form and including a control system for operating the device to diffuse the compound into the air within the space to be treated; providing the control system of the diffusion device with a sensor in fluid communication with the air within the space to be treated, the sensor configured to sense the concentration of the compound aerosolized within the space to be treated; operating the diffusion device to diffuse the compound into the space to be treated; sensing the concentration of the compound within the space to be treated with the sensor and altering the operation of the diffusion device based on the concentration of the compound sensed within the space if necessary to achieve a desired concentration of compound within the space to be treated; providing a photoionization detection device operable to ionize the compound to be diffused into the space and to sense the ionization potential thereof; and repeating the sensing and altering step periodically to maintain the desired concentration of the compound within the space to be treated, wherein the photoionization detection device is configured to ionize the compound with an ionization potential of not greater than or equal to 9.6 eV.

2. The method of claim 1, further providing the space to be treated is to be disinfected and the compound is a liquid disinfection compound.

3. The method of claim 2, further comprising the compound is a glycol.

4. The method of claim 3, further comprising the compound is one of triethylene glycol and propylene glycol.

5. The method of claim 1, further comprising the control system including additional sensors monitoring other activity within the space to be treated and altering the operation of the diffusion device based on the sensing of such other activities within the space to be treated.

6. The method of claim 1, wherein the sensor includes a pair of photoionization detection devices that are used in combination to reduce the possible false determination of the concentration of the compound within the space based on the presence of other compounds having similar ionization potentials.

7. A liquid diffusion device for treating a space with a liquid compound, the liquid diffusion device comprising: a control system for operating the liquid diffusion device to diffuse the compound into the space to be treated; the control system including a sensor in fluid communication with the air in the space to be treated, the sensor configured to sense the concentration of the compound within the air of the space to be treated; and the control system configured to alter the operation of the liquid diffusion device based on the concentration of compound sensed within the space to be treated and a desired concentration of that compound; the device further comprising a photoionization detection device operable to ionize the compound to be diffused into the space and to sense the ionization potential thereof, wherein the photoionization detection device is configured to ionize the compound with an ionization potential of not greater than or equal to 9.6 eV.

8. The liquid diffusion device of claim 7, further comprising the control system including a feedback loop for the operation of the liquid diffusion device, with the sensor periodically sensing the concentration of the compound and the control system altering operation of the liquid diffusion device based on each sensed concentration of compound sensed by the sensor.

9. The liquid diffusion device of claim 7, the control system further comprising at least one additional sensor to sense activity within the space to be treated and altering the operation of the liquid diffusion device based on activity within the space sensed by the at least one additional sensor.

10. The method of claim 7, wherein the sensor includes a pair of photoionization detection devices that are used in combination to reduce the possible false determination of the concentration of the compound within the space based on the presence of other compounds having similar ionization potentials.

11. A compound diffusion device for treating a space, comprising a control system; a diffusing means operatively controlled by the control system to aerosolize a compound into the space; a sensor controller by the control system to detect a concentration level of the aerosolized compound in the space; and a photoionizer controlled by the control system to ionize the aerosolized compound and to detect an ionization potential thereof, wherein the control system is operable to control operation of the diffusing means and the photoionizer based on the detected concentration level and the detected ionization potential of the aerosolized compound in the space, wherein the photoionizer is operable to ionize the aerosolized compound with an ionization potential of not greater than or equal to 9.6 eV.

12. The compound diffusion device of claim 11, wherein the compound is a glycol.

13. The compound diffusion device of claim 12, wherein the compound is one of triethylene glycol and propylene glycol.