CA2732541A1 - Desiccant drying system and method of operation thereof - Google Patents
Desiccant drying system and method of operation thereof Download PDFInfo
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- CA2732541A1 CA2732541A1 CA 2732541 CA2732541A CA2732541A1 CA 2732541 A1 CA2732541 A1 CA 2732541A1 CA 2732541 CA2732541 CA 2732541 CA 2732541 A CA2732541 A CA 2732541A CA 2732541 A1 CA2732541 A1 CA 2732541A1
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- dew point
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/0454—Controlling adsorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/26—Drying gases or vapours
- B01D53/261—Drying gases or vapours by adsorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2259/00—Type of treatment
- B01D2259/40—Further details for adsorption processes and devices
- B01D2259/40083—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption
- B01D2259/40088—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption by heating
- B01D2259/4009—Regeneration of adsorbents in processes other than pressure or temperature swing adsorption by heating using hot gas
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2259/00—Type of treatment
- B01D2259/40—Further details for adsorption processes and devices
- B01D2259/402—Further details for adsorption processes and devices using two beds
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Abstract
Disclosed herein is a desiccant drying system, and method of operation thereof, wherein a regeneration cycle implemented in respect of the system's two or more desiccant towers is initiated and/or controlled as a function of one or more environmental, process and/or system parameters, such as an ambient air dew point, process air dew point, and the like.
Description
i DESICCANT DRYING SYSTEM AND METHOD OF OPERATION THEREOF
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to desiccant drying systems, and in particular, to multiple chamber desiccant drying systems and methods of operation thereof.
BACKGROUND
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to desiccant drying systems, and in particular, to multiple chamber desiccant drying systems and methods of operation thereof.
BACKGROUND
[0002] Compressed air dryers comprising two or more desiccant towers are generally known in the art, whereby, while one tower (the operating tower) is drying compressed air for use in plant operations, the other tower (the regenerating tower) is being regenerated. Regeneration of a desiccant tower in such known systems generally includes a heating step, where ambient air is heated and blown through the desiccant tower to drive off the collected moisture, and a cooling step, where a fraction of the compressed dry air from the operating desiccant tower is preferably used to cool the desiccant.
Namely, process air is generally utilized in the regeneration cooling cycle as it is generally recognized that the application of unheated ambient air in the cooling phase reintroduces moisture into the regenerating tower, thereby reducing the efficiency of the desiccant from the start. The use of a cooling ambient air source is thus generally discouraged in the art. The preferred use of compressed air as provided from the operating desiccant tower, however, has for effect of decreasing the efficiency of the operating tower, in some examples, using up to 5-7% of its output; this is a problem especially during peak demand for the dry, compressed air.
Namely, process air is generally utilized in the regeneration cooling cycle as it is generally recognized that the application of unheated ambient air in the cooling phase reintroduces moisture into the regenerating tower, thereby reducing the efficiency of the desiccant from the start. The use of a cooling ambient air source is thus generally discouraged in the art. The preferred use of compressed air as provided from the operating desiccant tower, however, has for effect of decreasing the efficiency of the operating tower, in some examples, using up to 5-7% of its output; this is a problem especially during peak demand for the dry, compressed air.
[0003] One example of such systems is provided in U.S. Patent No. 6,336,278 to Crawford et al., wherein a method and system for controlling airflow in a desiccant drying system having two desiccant beds is disclosed. The disclosed system comprises a first diverter valve that communicates with each of the desiccant beds, a regeneration air inlet, and a process air outlet, and a second diverter valve that communicates with each of the desiccant beds, a process air inlet, and a regeneration air outlet. A
first of the beds is HON-ADO/CDA
regenerated by moving the first diverter valve to a position in which the first bed communicates with the regeneration air inlet and a second of the beds communicates with the process air outlet, and by moving the second diverter valve to a position in which the first bed communicates with the regeneration air outlet and the second bed communicates with the process air inlet. The first bed is subsequently cooled by moving the first diverter valve to an intermediate cooling position in which the second bed communicates with both of the process air outlet and the first bed, and closing the regeneration air inlet.
first of the beds is HON-ADO/CDA
regenerated by moving the first diverter valve to a position in which the first bed communicates with the regeneration air inlet and a second of the beds communicates with the process air outlet, and by moving the second diverter valve to a position in which the first bed communicates with the regeneration air outlet and the second bed communicates with the process air inlet. The first bed is subsequently cooled by moving the first diverter valve to an intermediate cooling position in which the second bed communicates with both of the process air outlet and the first bed, and closing the regeneration air inlet.
[0004] U.S. Patent No. 6,729,039 to Crawford provides another example, wherein a method and an apparatus for controlling airflow in a desiccant drying system having two desiccant beds is disclosed. In this example, first and second regeneration air control valves are also provided which during a cooling phase of the regeneration cycle admit a cooling bleed stream of process air to the desiccant bed being regenerated and then convey the cooling air bleed stream from the desiccant bed and through a heat exchanger back to the process air inlet.
[0005] As expressed in these examples, the use of process air in the cooling phase of a regeneration cycle is highly favoured over the use of ambient air in avoiding the introduction of moisture into the regenerating tower, as commonly accepted in the art.
While some consideration is provided in these examples as to the effect the use of process gas in the regeneration cooling phase may have on the operational parameters of the system (e.g. spikes in process gas temperature and dew point), the impact of using a significant percentage of the process air stream for regeneration cooling is not fully appreciated.
[0005] Therefore, there remains a need for a desiccant drying system and method of operation thereof that overcome some of the drawbacks of known technologies, or at least, provides the public with a useful alternative.
[0007] This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily HON-ADO/CDA
}
intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.
SUMMARY
[0008] An object of the invention is to provide a desiccant drying system and method of operation thereof. In accordance with an embodiment of the invention, there is provided a desiccant drying system, comprising: at least two desiccant chambers; an ambient air dew point monitor; multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to: divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber, a composition of said cooling air being selectively adjusted via controller operation of said multiple air diversion mechanisms responsive to said ambient air dew point monitor.
[0009] In accordance with another embodiment of the invention, there is provided a desiccant drying system, comprising: at least two desiccant chambers; an ambient air dew point monitor; multiple ambient and process air channeling and diversion mechanisms;
and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to: divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber in accordance with one of at least two HON-ADO/CDA
preset regeneration cooling cycles selected by said controller responsive to said ambient air dew point monitor, at least one of said preset regeneration cooling cycles comprising ambient air cooling.
[0010] In accordance with another embodiment of the invention, there is provided a method for regenerating desiccant of a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of: detecting an ambient air dew point; heating the desiccant with heated ambient air; selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
[0011] In accordance with another embodiment of the invention, there is provided a computer-readable medium having encoded therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to control implementation of a regeneration cycle for a given desiccant chamber thereof as a function of a detected ambient air dew point by: directing heated ambient air through the given desiccant chamber; selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
[0012] In accordance with another embodiment of the invention, there is provided a method for automatically selecting when to initiate a desiccant regeneration cycle for a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of. monitoring a process duration and a process gas dew point for the given desiccant chamber in operation, and an ambient air dew point;
comparing said process gas dew point with a preset process dew point threshold; initiating regeneration upon said detected process gas dew point exceeding said preset process threshold; upon said process duration exceeding a preset process duration threshold and prior to said process gas dew point exceeding said preset process dew point threshold, comparing said HON-ADO/CDA
ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold. A computer-readable medium having encoded therein statements '.
and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the above method is also provided.
[0013] In accordance with another embodiment of the invention, there is provided a method for delaying initiation of a desiccant regeneration cycle beyond a preset process duration threshold in a multiple desiccant chamber drying system, the method comprising the steps of. monitoring a process duration, a process gas dew point and an ambient air dew point; upon said process duration exceeding the preset process duration threshold and prior to said process gas dew point exceeding a preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold. A computer-readable medium having encoded .15 therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the above method is also provided.
[0014] Other aims, objects, advantages and features of the invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0015] Several embodiments of the present disclosure will be provided, by way of examples only, with reference to the appended drawings, wherein:
[0016] Figure 1 is a schematic diagram of a desiccant drying system, in operation, wherein heated ambient air is used in a regeneration heating cycle, in accordance with one embodiment of the invention;
HON-ADO/CDA
[0017] Figure 2 is a schematic diagram of the desiccant drying system of Figure 1, wherein process air is used independently during at least a portion of the regeneration cooling cycle, in accordance with one embodiment of the invention;
[0018] Figure 3 is a schematic diagram of the desiccant drying system of Figure 1, wherein ambient air is used independently during at least a portion of a regeneration cooling cycle, in accordance with one embodiment of the invention;
[0019] Figure 4 is a schematic diagram of the desiccant drying system of Figure 1, wherein ambient air is. used in combination with process air during at least a portion of the regeneration cooling cycle, in accordance with one embodiment of the invention;
[0020] Figure 5 is a schematic diagram of a controller of a desiccant drying system, in accordance with one embodiment of the invention;
[0021] Figure 6 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof, in accordance with one .embodiment of the invention;
[0022] Figure 7 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof, in accordance with another embodiment of the invention; and [0023] Figure 8 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system in selecting when to initiate a regeneration cycle, in accordance with one embodiment of the invention.
DETAILED DESCRIPTION
[0024] It should be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood HON-ADO/CDA
that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected,"
"coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled" and variations thereof are not restricted to physical or mechanical or electrical connections or couplings. Furthermore, and as described in subsequent paragraphs, the specific mechanical or electrical configurations illustrated in .10 the drawings are intended to exemplify embodiments of the disclosure.
However, other alternative mechanical or electrical configurations are possible which are considered to be within the teachings of the instant disclosure. Furthermore, unless otherwise indicated, the term "or" is to be considered inclusive.
[0025] With reference to the disclosure herein and the appended figures, a desiccant drying system, and method of operation thereof, will now be described, in accordance with different embodiments of the invention. Contrary to known systems, in the embodiments of the systems considered herein, a regeneration cycle implemented in respect of the system's two or more desiccant towers is controlled as a function of one or more environmental, process and/or system parameters (e.g. ambient air dew point, process air dew point, etc.), such that an efficiency of the system can be increased relative to, for example, currently known systems for which regeneration cycles are initiated and implemented in accordance with a statically defined sequence of operations, that is operated following a same regeneration cycle sequence irrespective of environmental and/or process parameters.
[0026] For example, in one embodiment, the system judiciously uses ambient air to cool the desiccant during a cooling phase of a desiccant regeneration process.
Namely, and in accordance with one embodiment, the system is adapted to use cooling ambient air for at least a portion of the cooling phase in response to an ambient air dew point HON-ADO/CDA
measurement indicative that such use is in fact conducive to an improved system performance and/or efficiency. Namely, as will be described in greater detail below, the system may be configured to use one or more of exclusive ambient air cooling, simultaneous ambient and process air cooling, successive ambient and process air cooling, exclusive process air cooling, and/or different combinations thereof depending on a monitored ambient air dew point and the pre-determined effect use of cooling ambient air of such monitored dew point may have on the system as a whole.
Incorporating this level of intelligence in otherwise static systems allows for a decrease in the amount of process air used from the operating tower if and when appropriate given environmental conditions and a desired system output.
[0027) Depending on the complexity of the preset cooling cycles encoded within the system's controller, for example, the volume of ambient (atmospheric) air used for cooling can be based on the dew point (humidity) of the atmospheric air, and that, based on a number of preset dew point ranges, a gradual dew point index, and/or other such parameter definitions with which are associated respective cooling cycle parameters, such as will be described in greater detail below. For example, a greater volume of atmospheric air can be used in the winter when it is cold and the ambient dew point is relatively low, as compared to the summer when the dew point is relatively high.
Similarly, a same system may be configured differently depending where it is being deployed, for instance, in and or relatively wet climates, or again during different seasons in a same area where the ambient humidity levels may vary significantly from day to day, month to month, and/or season to season.
[00281 As will be described in greater detail below, the provision of different ambient air sources, whether from the exterior or interior of the plant or establishment where the system is implemented, may be readily applied in the present context, whereby the I
selected regeneration cooling cycle is aptly selected as a function of an appropriate dew point measurement of the air source of choice.
While some consideration is provided in these examples as to the effect the use of process gas in the regeneration cooling phase may have on the operational parameters of the system (e.g. spikes in process gas temperature and dew point), the impact of using a significant percentage of the process air stream for regeneration cooling is not fully appreciated.
[0005] Therefore, there remains a need for a desiccant drying system and method of operation thereof that overcome some of the drawbacks of known technologies, or at least, provides the public with a useful alternative.
[0007] This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily HON-ADO/CDA
}
intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.
SUMMARY
[0008] An object of the invention is to provide a desiccant drying system and method of operation thereof. In accordance with an embodiment of the invention, there is provided a desiccant drying system, comprising: at least two desiccant chambers; an ambient air dew point monitor; multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to: divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber, a composition of said cooling air being selectively adjusted via controller operation of said multiple air diversion mechanisms responsive to said ambient air dew point monitor.
[0009] In accordance with another embodiment of the invention, there is provided a desiccant drying system, comprising: at least two desiccant chambers; an ambient air dew point monitor; multiple ambient and process air channeling and diversion mechanisms;
and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to: divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber in accordance with one of at least two HON-ADO/CDA
preset regeneration cooling cycles selected by said controller responsive to said ambient air dew point monitor, at least one of said preset regeneration cooling cycles comprising ambient air cooling.
[0010] In accordance with another embodiment of the invention, there is provided a method for regenerating desiccant of a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of: detecting an ambient air dew point; heating the desiccant with heated ambient air; selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
[0011] In accordance with another embodiment of the invention, there is provided a computer-readable medium having encoded therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to control implementation of a regeneration cycle for a given desiccant chamber thereof as a function of a detected ambient air dew point by: directing heated ambient air through the given desiccant chamber; selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
[0012] In accordance with another embodiment of the invention, there is provided a method for automatically selecting when to initiate a desiccant regeneration cycle for a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of. monitoring a process duration and a process gas dew point for the given desiccant chamber in operation, and an ambient air dew point;
comparing said process gas dew point with a preset process dew point threshold; initiating regeneration upon said detected process gas dew point exceeding said preset process threshold; upon said process duration exceeding a preset process duration threshold and prior to said process gas dew point exceeding said preset process dew point threshold, comparing said HON-ADO/CDA
ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold. A computer-readable medium having encoded therein statements '.
and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the above method is also provided.
[0013] In accordance with another embodiment of the invention, there is provided a method for delaying initiation of a desiccant regeneration cycle beyond a preset process duration threshold in a multiple desiccant chamber drying system, the method comprising the steps of. monitoring a process duration, a process gas dew point and an ambient air dew point; upon said process duration exceeding the preset process duration threshold and prior to said process gas dew point exceeding a preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold. A computer-readable medium having encoded .15 therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the above method is also provided.
[0014] Other aims, objects, advantages and features of the invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0015] Several embodiments of the present disclosure will be provided, by way of examples only, with reference to the appended drawings, wherein:
[0016] Figure 1 is a schematic diagram of a desiccant drying system, in operation, wherein heated ambient air is used in a regeneration heating cycle, in accordance with one embodiment of the invention;
HON-ADO/CDA
[0017] Figure 2 is a schematic diagram of the desiccant drying system of Figure 1, wherein process air is used independently during at least a portion of the regeneration cooling cycle, in accordance with one embodiment of the invention;
[0018] Figure 3 is a schematic diagram of the desiccant drying system of Figure 1, wherein ambient air is used independently during at least a portion of a regeneration cooling cycle, in accordance with one embodiment of the invention;
[0019] Figure 4 is a schematic diagram of the desiccant drying system of Figure 1, wherein ambient air is. used in combination with process air during at least a portion of the regeneration cooling cycle, in accordance with one embodiment of the invention;
[0020] Figure 5 is a schematic diagram of a controller of a desiccant drying system, in accordance with one embodiment of the invention;
[0021] Figure 6 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof, in accordance with one .embodiment of the invention;
[0022] Figure 7 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof, in accordance with another embodiment of the invention; and [0023] Figure 8 is a flow diagram of a control sequence implemented by a controller of a desiccant drying system in selecting when to initiate a regeneration cycle, in accordance with one embodiment of the invention.
DETAILED DESCRIPTION
[0024] It should be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood HON-ADO/CDA
that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected,"
"coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled" and variations thereof are not restricted to physical or mechanical or electrical connections or couplings. Furthermore, and as described in subsequent paragraphs, the specific mechanical or electrical configurations illustrated in .10 the drawings are intended to exemplify embodiments of the disclosure.
However, other alternative mechanical or electrical configurations are possible which are considered to be within the teachings of the instant disclosure. Furthermore, unless otherwise indicated, the term "or" is to be considered inclusive.
[0025] With reference to the disclosure herein and the appended figures, a desiccant drying system, and method of operation thereof, will now be described, in accordance with different embodiments of the invention. Contrary to known systems, in the embodiments of the systems considered herein, a regeneration cycle implemented in respect of the system's two or more desiccant towers is controlled as a function of one or more environmental, process and/or system parameters (e.g. ambient air dew point, process air dew point, etc.), such that an efficiency of the system can be increased relative to, for example, currently known systems for which regeneration cycles are initiated and implemented in accordance with a statically defined sequence of operations, that is operated following a same regeneration cycle sequence irrespective of environmental and/or process parameters.
[0026] For example, in one embodiment, the system judiciously uses ambient air to cool the desiccant during a cooling phase of a desiccant regeneration process.
Namely, and in accordance with one embodiment, the system is adapted to use cooling ambient air for at least a portion of the cooling phase in response to an ambient air dew point HON-ADO/CDA
measurement indicative that such use is in fact conducive to an improved system performance and/or efficiency. Namely, as will be described in greater detail below, the system may be configured to use one or more of exclusive ambient air cooling, simultaneous ambient and process air cooling, successive ambient and process air cooling, exclusive process air cooling, and/or different combinations thereof depending on a monitored ambient air dew point and the pre-determined effect use of cooling ambient air of such monitored dew point may have on the system as a whole.
Incorporating this level of intelligence in otherwise static systems allows for a decrease in the amount of process air used from the operating tower if and when appropriate given environmental conditions and a desired system output.
[0027) Depending on the complexity of the preset cooling cycles encoded within the system's controller, for example, the volume of ambient (atmospheric) air used for cooling can be based on the dew point (humidity) of the atmospheric air, and that, based on a number of preset dew point ranges, a gradual dew point index, and/or other such parameter definitions with which are associated respective cooling cycle parameters, such as will be described in greater detail below. For example, a greater volume of atmospheric air can be used in the winter when it is cold and the ambient dew point is relatively low, as compared to the summer when the dew point is relatively high.
Similarly, a same system may be configured differently depending where it is being deployed, for instance, in and or relatively wet climates, or again during different seasons in a same area where the ambient humidity levels may vary significantly from day to day, month to month, and/or season to season.
[00281 As will be described in greater detail below, the provision of different ambient air sources, whether from the exterior or interior of the plant or establishment where the system is implemented, may be readily applied in the present context, whereby the I
selected regeneration cooling cycle is aptly selected as a function of an appropriate dew point measurement of the air source of choice.
HON-ADO/CDA
[0029] In a same or alternative embodiment, whereas known systems are configured to cyclically implement tower regeneration after every 8 or 12 hours of operation, for example, the drying system, in accordance with one embodiment of the invention, is configured to assess when best to initiate a regeneration cycle in response to one or more process and/or environmental factors such as process gas dew point, ambient dew point, process duration, etc. For example, by monitoring the dew point of the process gas entering the operating tower of the drying system, and initiating regeneration only in the event this process air dew point exceeds a predetermined threshold, significant improvements in system efficiency and performance can be achieved. For example, a given plant in which this system is implemented may require the provision of compressed dry air having a dew point of -15F. If the dew point of the, air entering the operating desiccant tower does not exceed that dew point, the regeneration cycle can be postponed either by a preset amount of time, as long as the monitored process air dew point does not exceed the preset dew point limit, or again as a function of an ambient air dew point which, in some embodiments, directly effects the performance characteristics of the regeneration and/or processing cycle. This improvement can be particularly useful in the winter months when the atmospheric air has a low dew point.
[0030] Referring now to Figure 1, a system, generally referred to using the numeral 100, and in accordance with an illustrative embodiment of the invention, will now be described. In this example, a first tower 102 and a second tower 104 of a twin tower desiccant drying system are schematically shown, each of which containing an adsorption medium (i.e. desiccant) for removing moisture from a process gas for use in various applications as would be readily appreciated by the skilled artisan. Each of the first and second towers communicates via a series of air channeling and diversion mechanisms, succinctly depicted herein by various channel segments (pipes) 106 and diverters (valves) 108 and 110. The first tower 102 and the second tower 104 may also be referred to as a "processing tower", or a "regeneration tower" based. on the mode of operation..
[0029] In a same or alternative embodiment, whereas known systems are configured to cyclically implement tower regeneration after every 8 or 12 hours of operation, for example, the drying system, in accordance with one embodiment of the invention, is configured to assess when best to initiate a regeneration cycle in response to one or more process and/or environmental factors such as process gas dew point, ambient dew point, process duration, etc. For example, by monitoring the dew point of the process gas entering the operating tower of the drying system, and initiating regeneration only in the event this process air dew point exceeds a predetermined threshold, significant improvements in system efficiency and performance can be achieved. For example, a given plant in which this system is implemented may require the provision of compressed dry air having a dew point of -15F. If the dew point of the, air entering the operating desiccant tower does not exceed that dew point, the regeneration cycle can be postponed either by a preset amount of time, as long as the monitored process air dew point does not exceed the preset dew point limit, or again as a function of an ambient air dew point which, in some embodiments, directly effects the performance characteristics of the regeneration and/or processing cycle. This improvement can be particularly useful in the winter months when the atmospheric air has a low dew point.
[0030] Referring now to Figure 1, a system, generally referred to using the numeral 100, and in accordance with an illustrative embodiment of the invention, will now be described. In this example, a first tower 102 and a second tower 104 of a twin tower desiccant drying system are schematically shown, each of which containing an adsorption medium (i.e. desiccant) for removing moisture from a process gas for use in various applications as would be readily appreciated by the skilled artisan. Each of the first and second towers communicates via a series of air channeling and diversion mechanisms, succinctly depicted herein by various channel segments (pipes) 106 and diverters (valves) 108 and 110. The first tower 102 and the second tower 104 may also be referred to as a "processing tower", or a "regeneration tower" based. on the mode of operation..
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[0031] It will be appreciated upon reference to the following description that various different channeling and diversion mechanism combinations and configurations may be considered herein to achieve similar results, and that, without departing from the general scope and nature of the present disclosure. Namely, various combinations and configurations of pipes, valves, inlets, outlets, compressors, blowers, diverters, and the like may be considered in designing a similar system without altering the general scope and advantage(s) of the various embodiments of the invention considered herein. For the sake of clarity and efficiency, the following thus concentrates on functionally depicting the system's constituent elements in operation rather than to enumerate the various structural possibilities that will be understood by the skilled artisan as falling within the scope of the present disclosure.
[0032] Following with this example, each of diverters 108 and 110 are controllable by controller 112 (operative control coupling shown by dash-dot lines) in order to direct airflow through the system during processing and regeneration. As will be discussed in greater detail below, the controller 112 in this embodiment is generally configured to adjust operation of the system in response to one or more dew point monitors 114. It will be appreciated that various types of operative/communicative couplings between the controller 112 and respective diversion mechanisms may be considered herein, such as wired, wireless, infrared and the like, without departing from the general scope and nature of the present disclosure.
[0033] In this particular example, we concentrate on the provision of an ambient air dew point monitor, in response to which, the system may aptly select an appropriate regeneration cycle, which, as depicted in Figure 1, is applied to regeneration tower 102 while processing tower 104 is operated to provide a supply of dry process air.
Again, it will be appreciated that different dew point and/or humidity monitors, sensors and/or detectors, whether local to the establishment where the system operates, or remote thereto (e.g. local/regional weather station data, etc.) may be considered to provide similar effects.
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[0034] Namely, a process gas inlet 116 (and blower 117) communicates with the diverter 108, which diverter 108 is shown in this configuration to direct a process gas flow into the processing tower 104, whereby moist process gas, for example process air, enters the process gas inlet 116 into the processing tower 104 to be dried thereby, i.e. by the desiccant thereof. Upon exiting the processing tower 104, the dried process gas is directed by diverter 110 to process gas outlet 118 from which it may be used in various processes of interest. In some embodiments, the process gas will be used in a substantially closed loop drying circuit in which dry process gas is flowed by or through a material to pick up moisture therefrom, which moisture is then carried back to the processing tower 104 via process gas inlet 116 to be captured by the desiccant thereof. In some embodiments, the process gas may be provided or replenished by various gas and/or air conditioning means, such as compressors, heaters, heat exchangers and the like. These and other such processes will be readily appreciated by the person of skill in the art as falling within the scope of this disclosure.
[0035] Simultaneously, the system 100 may be operated to regenerate the desiccant of tower 102, in this example, in accordance with a regeneration cycle selected as a function of a detected ambient air dew point. For instance, in this example, a regeneration gas inlet 120 (and blower 121), such as an ambient air inlet or the like, communicates with diverter 110 via heater 122, which heater 122 may be activated or not depending on the particular phase of the regeneration cycle. For instance, in a first phase of the regeneration cycle, a regeneration gas, for example ambient air, entering the regeneration gas inlet 120 is heated by the heater 122, and is directed by diverter 110 into the regeneration tower 102. The heated regeneration gas picks up moisture from the moist adsorption medium in this tower and is directed via diverter 108 to a regeneration gas outlet 124, which may communicate, for example, with the ambient atmosphere or with a heat exchanger (not shown) for recovery of heat energy. Alternatively, the regeneration outlet 124 may be directed so to contribute to the heating and humidifying of the plant or establishment in or for which the heating system is being used. In one example, the heating cycle consists of using blower 1.21 to blow 1000 efm of ambient air through an HON-ADO/CDA
electric heater (e.g. 120 KW heater) to heat the desiccant in regeneration tower 102 to approximately 450 F. The 1000 cfm hot and humid air may then be ejected outside, for example through the roof of the establishment, or again processed by a heat exchanger and/or used in the heating and humidifying of the establishment.
[0036] Once the heating cycle is completed, for example as prescribed by the selected regeneration cycle or again upon reaching a desired desiccant moisture level, the regeneration cycle proceeds to a cooling cycle (e.g. to reduce desiccant temperature to approximately 120 F in one example), in this example selected as a function of a detected ambient air dew point. For example, the controller 112 may be configured to select from two or more preset regeneration cooling cycles as a function of a detected ambient air dew point, or again compute appropriate cooling cycle parameters from this detected dew point. For the sake of simplicity, the following will discuss the provision of discretely defined cooling cycles (e.g. for respectively associated dew point ranges), however, as will be appreciated by the skilled artisan, the controller 112 may be configured to ,15 compute and implement particular cooling cycle parameters from a gradually varying index, and/or derived from one or more representative functions, to name a few examples.
[0037] For the purpose of illustration, different cooling cycle system configurations are depicted in Figures 2 to 4, wherein different combinations of these configurations may be implemented for different periods of time depending on the selected cooling cycle. Namely, in Figure 2, the system 100 is shown in a process air cooling cycle phase whereby diverter 110 is configured to allow a fraction of the process air exiting the process tower 104 to enter the regeneration tower 102 for cooling. As noted above, this particular approach to regeneration cooling is standard in the art and, while effective, is not the most efficient for significant process air losses may ensue. To recuperate some of this process air, diverter 108 could be configured to reintroduce the cooling process air into the process air circuit,. however, this generally has for effect to introduce further HON-ADO/CDA
moisture into the process air stream, or again generate a temperature increase, both often undesirable effects.
[00381 To mitigate this effect, where an ambient air dew point as monitored by dew point monitor 114 is favourably identified, at least some of the cooling phase may make use of ambient air, for example as shown in Figures 3 and 4. In Figure 3, the heater 122 is deactivated upon completion of the heating phase while ambient air continues to flow through the regeneration tower 102 for a given period of time, for example, as prescribed by the selected cooling cycle. As described above, the ambient air then exits the regeneration tower 102 by way of diverter 108. This particular approach may be used to advantage, for example, where the ambient dew point is deemed sufficiently low to have limited impact on the introduction of moisture into the regeneration tower 102, for example on cold days (e.g. during the cold winter months in certain regions) or again in and climates. Accordingly, upon identification of an appropriately low dew point via monitor 114, the controller 1 12 may elect to implement an ambient air cooling phase.
[00391 In some circumstances, however, the controller 112 may be further configured to implement a split cooling cycle, whereby a first phase of the cooling cycle consists of an ambient air cooling phase, as shown in Figure 3 for example, followed by a process air cooling phase, as shown in Figure 2 for example. Using this combined approach, at least some of the process air loss during regeneration is reduced while the amount of moisture introduced into the regeneration tower 102 by way of ambient air cooling is also reduced.
[0040] In some embodiments, the controller 112 may be configured to selectivel 1 ~ Y Y
adjust the ratio of time for each cooling phase, for instance, by adjusting a duration of the relative ambient cooling phase relative to a process air cooling phase. For example, the ambient air cooling period may be adjusted from 0% to 100% of a total cooling period, either gradually as a function of a stored ambient air dew point function or index, or discretely as a function of stored ambient air dew point ranges associated with respective preset cooling cycle parameters. It will be understood that, in some climates or applications, a 100% ambient air cooling cycle may not be reasonably applied, whereby HON-ADO/CDA
appropriate ratios may be more conservatively defined (e.g. 20% to 70%), while still achieving improvements in the reduction of process air loss during regeneration.
[0041] Referring now to Figure 4, the system may also or alternatively be configured to implement a combined regeneration cooling cycle wherein both ambient and process air are used concurrently for cooling. In this example, ambient air is again provided via regeneration gas inlet 120 (with heater 122 deactivated), however, diverter 110 is configured to direct both the input ambient air and a fraction of the process air exiting processing tower 104, into regeneration tower 102. In such embodiments, diverter 110, which may include a single or distinct valves and the like, may be further operated by controller 112 to provide a preset volumetric ratio of ambient to process air.
For example, while a simplified embodiment may allow only one preset combination of cooling air to enter the regeneration chamber 102, a more complex diverting mechanism may allow for a number of continuous or discrete combinations thus allowing for greater control of the regeneration process, and thus greater optimization of an efficiency thereof.
[0042] In different embodiments, the system may be configured to select form one or more of the above-described cooling cycles, and between different parameters respective thereof, such as cycle periods, gas volumes and/or ratios, sequences, and the like.
Depending on the complexity and precision of the system's air channeling and diversion mechanisms, various degrees of control may be achieved to varying effects.
Namely, in simplified systems, a selection between two or three preset cooling cycles may allow for sufficient improvements in system efficiency, whereas more complex systems may allow for a gradual variation between various discretely or continuously defined cooling cycles, thus achieving greater control of the system's performance.
[0043] Referring now to Figures 6 and 7, different embodiments of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof are shown. In particular, Figure 6 illustrates initiation of the regeneration process at step 602, followed by a heating cycle at step 604 consisting generally, but not exclusively, of an ambient air heating cycle, whereby ambient air is heated and blown HON-ADO/CDA
through the regeneration chamber to heat and dry the desiccant thereof. Upon completion of the heating cycle, an appropriate cooling cycle is selected at step 606 as a function of a detected/monitored ambient dew point value 608 accessible to the controller.
In this embodiment, selection of the cooling cycle is made from a series of preset cycles numbered 1 to N, wherein in the driest of ambient conditions (low dew point), the cooling cycle may consist exclusively of an ambient cooling phase (cycle 1), whereas in the most humid conditions (high dew point), the cooling cycle may consist exclusively of a process gas cooling phase (cycle N), with different combined successive ambient and cooling gas phases falling therebetween as cycles 2 to N-1.
[0044] As will be appreciated by the skilled artisan, the provision of only two preset cooling cycles may allow for significant regeneration cycle performance and efficiency gains, whereas the provision of a greater scale of available preset cooling cycles may allow for even greater improvements. Also, while cycles 1 and N are depicted as defined by an exclusive ambient and process gas cooling phase respectively, it will be appreciated that preset cycles may avoid these extremes, but rather include a number of gradually varying ambient and process gas cooling phase combinations. Upon completion of the selected cooling cycle, the regeneration cycle ends at step 610.
[0045] In the embodiment of Figure 7, the regeneration process is initiated at step 702, followed by a heating cycle at step 704, as in the embodiment of Figure 6. Upon completion of the heating cycle, an appropriate cooling cycle is again selected at step 706 as a function of a detected/monitored ambient dew point value 708 accessible to the controller. In this embodiment, however, selection of the cooling cycle is made from a series of preset cycles numbered 1 to N, wherein a varying combination ratio of ambient to process gas is used depending on the detected ambient air dew point.
Namely, in the driest of ambient conditions (low dew point), the cooling gas composition of the cooling cycle may consist of a relatively high ambient air component as compared to a relatively low process gas component. Conversely, in the most humid conditions (high dew point), the cooling gas composition of the cooling cycle may consist of a relatively low ambient HON-ADO/CDA
air component as compared to a relatively high process gas component, with gradually varying compositions falling therebetween.
[0046] Again, as will be appreciated by the skilled artisan, the provision of only two preset cooling cycles may allow for significant regeneration cycle performance and efficiency gains, whereas the provision of a greater scale of available preset cooling cycles may allow for even greater improvements. Also, while each embodiment is depicted in exclusivity, it will be appreciated that the selected cooling gas composition may include a succession of distinctly characterized cooling phases, each one of which comprising ambient air or process gas independently, and/or comprising a selected composition ratio thereof. These and other such considerations are therefgre considered to fall within the scope of the present disclosure. Upon completion of the selected cooling cycle, the regeneration cycle ends at step 710.
[0047] In any of the above cases, and with reference again to Figures 1 to 4, once the cooling cycle has been completed, the regeneration tower 102 is either isolated to preserve its dryness, or again used for processing, whereby the processing tower 104 may then be itself regenerated, with appropriate reversal of the system's diversion mechanisms.
[0048] For example, in one embodiment, the processing tower is brought offline for regeneration periodically, in accordance with a prescribed regeneration schedule. For example, regeneration may be prescribed every 8 or 12 hours such that each tower is operated as processing tower for half or a third of each day, such as may be the case in a processing plant operated around the clock. In another embodiment, however, the processing tower may be operated as such as long as its operating conditions meet certain requirements. For instance, in one example, a dew point monitor is operated at the inlet and/or outlet of the processing tower so to monitor a humidity level thereof.
In such system, the processing tower may remain online as long as the dew point (humidity) of the process gas does not go above a certain degree, at which point a regeneration cycle is HON-ADO/CDA
initiated. Using this approach, regeneration is only applied when needed, thus increasing an overall efficiency of the system.
[0049] In another embodiment, the regeneration cycle initiation may rather be selected as a function of a number of parameters, for example including, but not limited to, process gas inlet dew point, process gas outlet dew point, ambient air dew point, process duration, etc. For example, with reference to Figure 8, and in accordance with one embodiment of the invention, a control sequence implemented by a controller of a desiccant drying system in selecting when to initiate a regeneration cycle is schematically illustrated. In this embodiment, a processing cycle is initiated at step 802.
During this to process, the controller monitors a process dew point (803) for comparison with a preset threshold therefor. Upon identifying at decision step 804 that the process dew point exceeds its threshold, regeneration is automatically initiated at step 806.
[0050] At the same time, the controller monitors a processing time or duration for this cycle and, until this time exceeds a preset threshold therefor at decision step 808, the process continues unimpeded. Once the duration exceeds its threshold, however, and prior to the process dew point exceeding its threshold, the controller accesses a current ambient air dew point (809) at decision step 810 and, should this ambient dew point exceed a preset threshold therefor, regeneration is initiated at step 806.
Otherwise, the process continues until either the process dew point 803 or the ambient dew point 809 exceeds its respective threshold, as determined at decision step 812. Applying this delayed approach to regeneration initiation, as will be demonstrated in the following examples, allows for significant energy savings as regeneration is only implemented when deemed necessary and energetically favourable.
[0051] As will be appreciated by the skilled artisan, additional system components may be considered in the present context to further assist in the control and redirection of gas flows within the system. For example, cutoff valves may be used at different locations within the system to isolate certain components of the system, namely, the regeneration tower once the regeneration cycle has been completed, or again both towers HON-ADO/CDA
in the event the entire system is shutoff, so to preserve the dryness of the desiccant between uses. Similarly, while a single ambient air inlet has been depicted in providing ambient air for both ambient air heating and cooling, distinct ambient air inlets may also be contemplated, as can different ambient air sources be considered (e.g.
outside air, air from within a processing plant or establishment where the system is being operated, etc.).
Also, while no specific mention is made in the above-referenced figures as to where and how the regeneration air may be used upon exiting the regeneration tower, it will be appreciated that the moist air thus provided may be used, for example, in heating and humidifying the establishment in which the system is operated, for certain processes where warm moist air may be of use, processed through a heat exchanger to recuperate heat energy therefrom, or again simply released outside.
[0052] With reference to Figure 5, a controller, generally referred to using the numeral 200, and in accordance with one embodiment of the invention, will now be described. In this embodiment, the controller is configured to have access to ambient air dew point data from an internal or external dew point monitor (or sensor), and control operation of at least some of the system's various gas diversion mechanisms in response thereto. For instance, the controller, as described above, may be configured to select from a series of preset regeneration cooling cycles, a cooling cycle associated with a current ambient air dew point, thus improving system performance characteristics. The controller may also, or alternatively, select when to implement a new regeneration cycle based, in part, on the detected ambient air dew point. These options are described in greater detail above with reference to Figures I to 4 and 6 to 8, and below with reference to the following examples.
[0053] In this illustrative embodiment, the controller is diagrammatically depicted to comprise a power supply 202 (e.g. line and/or battery power source), an input/output 204 (e.g. for input of control parameters, cycle data/parameters, system updates, etc., and output of performance data, past/current/upcoming cycle parameters, version code, status, etc.), and user interface 210, which may include an integrated, local and/or remote is HON-ADOICDA.
interface for user interaction with the system's control protocols and/or data. The controller further comprises one or more computer-readable media 208 for storing preset cooling cycles, system operation controls, regeneration initiation protocols, and the like, and one or more processors 206 for implementing same. As will be appreciated by the skilled artisan, the controller 200 may take various forms such as a dedicated system specific computing device, a programmed general purpose computing device (e.g.
desktop, laptop, etc.), or other such self-standing computing platform, or again consist or form part of a system control module implemented within the context of a larger system or plant-wide computer control platform, or the like. These and other such considerations to will be apparent to the person of ordinary skill in the art, and should therefore be considered to fall within the scope of the present disclosure.
[0054] Reference will now be made to the following non-limiting examples, in which sample results are provided with respect to exemplary embodiments of the invention.
Example 1 [0055] The following provides an example of preset ambient air cooling periods selected as a function of ambient air dew point, thus providing for increased system performance and efficiency in implementing a regeneration cycle, in accordance with one embodiment of the invention.
[0056] In this particular example, a process air outlet dew point threshold was set at -15 F. In the event that the process air outlet dew point exceeded this threshold, regeneration was initiated immediately. Unless this threshold was reached, however, regeneration was only initiated in the event that more than 8 hours had passed since the last regeneration and that the ambient air dew point was greater than -5 C .
Using this approach, the desiccant life is extended while regeneration cycles and times could be reduced as well as energy consumption by the heaters and blowers.
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[0057] Once the regeneration is initiated, the regenerating tower is first exposed to a heating cycle lasting approximately 140 minutes (heated ambient air), followed by a cooling cycle selected as a function of detected ambient dew point. Namely, the cooling cycle in this example consisted of a precooling period of ambient air cooling, followed by process air cooling period. The table below provides different precooling period durations as a function of detected ambient air dew point temperature ranges, which allows for a reduction in the usage of expensive dry air during the cooling phase. In one embodiment, specific cooling periods may be adjusted by way of a PID controller or the like, thus {
providing greater improvements in system control and performance.
to Outside Air Dew point Pre cool minute temperature C (ambient air) <-10 85 -lO to 0 75 0 to 5 45 5 to 10 35 >15 25 [0058] In this example, if one considers a total cooling period of approximately 2 hours, the ambient air cooling period will consist of between 20% and 70% of this total cooling period, depending on ambient air dew point, thus representing in even the worst of cases, a significant reduction in process air cooling and losses.
Example 2 [0059] The following provides some observed performance parameters in implementing some of the above improvements, in accordance with some embodiments of the invention.
[0060] In a first test, the process air set point was adjusted to approximately -15F
from -40F, and the controller was set to only implement regeneration upon the set point being reached, or upon more than 8 hours passing since the last regeneration and the outside air reaching a dew point above -5 C. For example, when sourcing or replenishing HON-ADOICDA
process gas from an ambient air source, namely via one or more gas conditioning means such as compressors, heaters, exchangers and the like, for example, the load imposed on the conditioning means and/or desiccant will be significantly lessened when the dew point of this ambient air source is lower, thus delaying the need for regeneration.
Alternatively, when the dew point of the process air source becomes higher, it may become energetically favourable to regenerate the desiccant more regularly given the increased load thereon and/or process gas conditioning means. Using these parameters during the cold winter months in Canadian plants, it was observed that on average, two regenerations were saved every week on all dryers, resulting for this particular test in a combined power savings in the order of 70,000KWh.
[0061] Furthermore, upon discharging heating air into the plant rather than outside, a heating gas savings of approximately 25,500 cubic meters was observed.
[0062] Also, upon applying mixed air cooling consistent with the preset values listed above, compressed process air savings in the order of 96,000,000 cubic feet were observed, resulting in power savings in the order of 350,000KWh.
[0063] While extra energy was expended in running the blowers during ambient air cooling, overall, power savings in the order to 400,000KWh where observed.
[0064] While the present disclosure describes various exemplary embodiments, the disclosure is not so limited. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
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[0031] It will be appreciated upon reference to the following description that various different channeling and diversion mechanism combinations and configurations may be considered herein to achieve similar results, and that, without departing from the general scope and nature of the present disclosure. Namely, various combinations and configurations of pipes, valves, inlets, outlets, compressors, blowers, diverters, and the like may be considered in designing a similar system without altering the general scope and advantage(s) of the various embodiments of the invention considered herein. For the sake of clarity and efficiency, the following thus concentrates on functionally depicting the system's constituent elements in operation rather than to enumerate the various structural possibilities that will be understood by the skilled artisan as falling within the scope of the present disclosure.
[0032] Following with this example, each of diverters 108 and 110 are controllable by controller 112 (operative control coupling shown by dash-dot lines) in order to direct airflow through the system during processing and regeneration. As will be discussed in greater detail below, the controller 112 in this embodiment is generally configured to adjust operation of the system in response to one or more dew point monitors 114. It will be appreciated that various types of operative/communicative couplings between the controller 112 and respective diversion mechanisms may be considered herein, such as wired, wireless, infrared and the like, without departing from the general scope and nature of the present disclosure.
[0033] In this particular example, we concentrate on the provision of an ambient air dew point monitor, in response to which, the system may aptly select an appropriate regeneration cycle, which, as depicted in Figure 1, is applied to regeneration tower 102 while processing tower 104 is operated to provide a supply of dry process air.
Again, it will be appreciated that different dew point and/or humidity monitors, sensors and/or detectors, whether local to the establishment where the system operates, or remote thereto (e.g. local/regional weather station data, etc.) may be considered to provide similar effects.
HON-ADO/CDA
[0034] Namely, a process gas inlet 116 (and blower 117) communicates with the diverter 108, which diverter 108 is shown in this configuration to direct a process gas flow into the processing tower 104, whereby moist process gas, for example process air, enters the process gas inlet 116 into the processing tower 104 to be dried thereby, i.e. by the desiccant thereof. Upon exiting the processing tower 104, the dried process gas is directed by diverter 110 to process gas outlet 118 from which it may be used in various processes of interest. In some embodiments, the process gas will be used in a substantially closed loop drying circuit in which dry process gas is flowed by or through a material to pick up moisture therefrom, which moisture is then carried back to the processing tower 104 via process gas inlet 116 to be captured by the desiccant thereof. In some embodiments, the process gas may be provided or replenished by various gas and/or air conditioning means, such as compressors, heaters, heat exchangers and the like. These and other such processes will be readily appreciated by the person of skill in the art as falling within the scope of this disclosure.
[0035] Simultaneously, the system 100 may be operated to regenerate the desiccant of tower 102, in this example, in accordance with a regeneration cycle selected as a function of a detected ambient air dew point. For instance, in this example, a regeneration gas inlet 120 (and blower 121), such as an ambient air inlet or the like, communicates with diverter 110 via heater 122, which heater 122 may be activated or not depending on the particular phase of the regeneration cycle. For instance, in a first phase of the regeneration cycle, a regeneration gas, for example ambient air, entering the regeneration gas inlet 120 is heated by the heater 122, and is directed by diverter 110 into the regeneration tower 102. The heated regeneration gas picks up moisture from the moist adsorption medium in this tower and is directed via diverter 108 to a regeneration gas outlet 124, which may communicate, for example, with the ambient atmosphere or with a heat exchanger (not shown) for recovery of heat energy. Alternatively, the regeneration outlet 124 may be directed so to contribute to the heating and humidifying of the plant or establishment in or for which the heating system is being used. In one example, the heating cycle consists of using blower 1.21 to blow 1000 efm of ambient air through an HON-ADO/CDA
electric heater (e.g. 120 KW heater) to heat the desiccant in regeneration tower 102 to approximately 450 F. The 1000 cfm hot and humid air may then be ejected outside, for example through the roof of the establishment, or again processed by a heat exchanger and/or used in the heating and humidifying of the establishment.
[0036] Once the heating cycle is completed, for example as prescribed by the selected regeneration cycle or again upon reaching a desired desiccant moisture level, the regeneration cycle proceeds to a cooling cycle (e.g. to reduce desiccant temperature to approximately 120 F in one example), in this example selected as a function of a detected ambient air dew point. For example, the controller 112 may be configured to select from two or more preset regeneration cooling cycles as a function of a detected ambient air dew point, or again compute appropriate cooling cycle parameters from this detected dew point. For the sake of simplicity, the following will discuss the provision of discretely defined cooling cycles (e.g. for respectively associated dew point ranges), however, as will be appreciated by the skilled artisan, the controller 112 may be configured to ,15 compute and implement particular cooling cycle parameters from a gradually varying index, and/or derived from one or more representative functions, to name a few examples.
[0037] For the purpose of illustration, different cooling cycle system configurations are depicted in Figures 2 to 4, wherein different combinations of these configurations may be implemented for different periods of time depending on the selected cooling cycle. Namely, in Figure 2, the system 100 is shown in a process air cooling cycle phase whereby diverter 110 is configured to allow a fraction of the process air exiting the process tower 104 to enter the regeneration tower 102 for cooling. As noted above, this particular approach to regeneration cooling is standard in the art and, while effective, is not the most efficient for significant process air losses may ensue. To recuperate some of this process air, diverter 108 could be configured to reintroduce the cooling process air into the process air circuit,. however, this generally has for effect to introduce further HON-ADO/CDA
moisture into the process air stream, or again generate a temperature increase, both often undesirable effects.
[00381 To mitigate this effect, where an ambient air dew point as monitored by dew point monitor 114 is favourably identified, at least some of the cooling phase may make use of ambient air, for example as shown in Figures 3 and 4. In Figure 3, the heater 122 is deactivated upon completion of the heating phase while ambient air continues to flow through the regeneration tower 102 for a given period of time, for example, as prescribed by the selected cooling cycle. As described above, the ambient air then exits the regeneration tower 102 by way of diverter 108. This particular approach may be used to advantage, for example, where the ambient dew point is deemed sufficiently low to have limited impact on the introduction of moisture into the regeneration tower 102, for example on cold days (e.g. during the cold winter months in certain regions) or again in and climates. Accordingly, upon identification of an appropriately low dew point via monitor 114, the controller 1 12 may elect to implement an ambient air cooling phase.
[00391 In some circumstances, however, the controller 112 may be further configured to implement a split cooling cycle, whereby a first phase of the cooling cycle consists of an ambient air cooling phase, as shown in Figure 3 for example, followed by a process air cooling phase, as shown in Figure 2 for example. Using this combined approach, at least some of the process air loss during regeneration is reduced while the amount of moisture introduced into the regeneration tower 102 by way of ambient air cooling is also reduced.
[0040] In some embodiments, the controller 112 may be configured to selectivel 1 ~ Y Y
adjust the ratio of time for each cooling phase, for instance, by adjusting a duration of the relative ambient cooling phase relative to a process air cooling phase. For example, the ambient air cooling period may be adjusted from 0% to 100% of a total cooling period, either gradually as a function of a stored ambient air dew point function or index, or discretely as a function of stored ambient air dew point ranges associated with respective preset cooling cycle parameters. It will be understood that, in some climates or applications, a 100% ambient air cooling cycle may not be reasonably applied, whereby HON-ADO/CDA
appropriate ratios may be more conservatively defined (e.g. 20% to 70%), while still achieving improvements in the reduction of process air loss during regeneration.
[0041] Referring now to Figure 4, the system may also or alternatively be configured to implement a combined regeneration cooling cycle wherein both ambient and process air are used concurrently for cooling. In this example, ambient air is again provided via regeneration gas inlet 120 (with heater 122 deactivated), however, diverter 110 is configured to direct both the input ambient air and a fraction of the process air exiting processing tower 104, into regeneration tower 102. In such embodiments, diverter 110, which may include a single or distinct valves and the like, may be further operated by controller 112 to provide a preset volumetric ratio of ambient to process air.
For example, while a simplified embodiment may allow only one preset combination of cooling air to enter the regeneration chamber 102, a more complex diverting mechanism may allow for a number of continuous or discrete combinations thus allowing for greater control of the regeneration process, and thus greater optimization of an efficiency thereof.
[0042] In different embodiments, the system may be configured to select form one or more of the above-described cooling cycles, and between different parameters respective thereof, such as cycle periods, gas volumes and/or ratios, sequences, and the like.
Depending on the complexity and precision of the system's air channeling and diversion mechanisms, various degrees of control may be achieved to varying effects.
Namely, in simplified systems, a selection between two or three preset cooling cycles may allow for sufficient improvements in system efficiency, whereas more complex systems may allow for a gradual variation between various discretely or continuously defined cooling cycles, thus achieving greater control of the system's performance.
[0043] Referring now to Figures 6 and 7, different embodiments of a control sequence implemented by a controller of a desiccant drying system during a regeneration cycle thereof are shown. In particular, Figure 6 illustrates initiation of the regeneration process at step 602, followed by a heating cycle at step 604 consisting generally, but not exclusively, of an ambient air heating cycle, whereby ambient air is heated and blown HON-ADO/CDA
through the regeneration chamber to heat and dry the desiccant thereof. Upon completion of the heating cycle, an appropriate cooling cycle is selected at step 606 as a function of a detected/monitored ambient dew point value 608 accessible to the controller.
In this embodiment, selection of the cooling cycle is made from a series of preset cycles numbered 1 to N, wherein in the driest of ambient conditions (low dew point), the cooling cycle may consist exclusively of an ambient cooling phase (cycle 1), whereas in the most humid conditions (high dew point), the cooling cycle may consist exclusively of a process gas cooling phase (cycle N), with different combined successive ambient and cooling gas phases falling therebetween as cycles 2 to N-1.
[0044] As will be appreciated by the skilled artisan, the provision of only two preset cooling cycles may allow for significant regeneration cycle performance and efficiency gains, whereas the provision of a greater scale of available preset cooling cycles may allow for even greater improvements. Also, while cycles 1 and N are depicted as defined by an exclusive ambient and process gas cooling phase respectively, it will be appreciated that preset cycles may avoid these extremes, but rather include a number of gradually varying ambient and process gas cooling phase combinations. Upon completion of the selected cooling cycle, the regeneration cycle ends at step 610.
[0045] In the embodiment of Figure 7, the regeneration process is initiated at step 702, followed by a heating cycle at step 704, as in the embodiment of Figure 6. Upon completion of the heating cycle, an appropriate cooling cycle is again selected at step 706 as a function of a detected/monitored ambient dew point value 708 accessible to the controller. In this embodiment, however, selection of the cooling cycle is made from a series of preset cycles numbered 1 to N, wherein a varying combination ratio of ambient to process gas is used depending on the detected ambient air dew point.
Namely, in the driest of ambient conditions (low dew point), the cooling gas composition of the cooling cycle may consist of a relatively high ambient air component as compared to a relatively low process gas component. Conversely, in the most humid conditions (high dew point), the cooling gas composition of the cooling cycle may consist of a relatively low ambient HON-ADO/CDA
air component as compared to a relatively high process gas component, with gradually varying compositions falling therebetween.
[0046] Again, as will be appreciated by the skilled artisan, the provision of only two preset cooling cycles may allow for significant regeneration cycle performance and efficiency gains, whereas the provision of a greater scale of available preset cooling cycles may allow for even greater improvements. Also, while each embodiment is depicted in exclusivity, it will be appreciated that the selected cooling gas composition may include a succession of distinctly characterized cooling phases, each one of which comprising ambient air or process gas independently, and/or comprising a selected composition ratio thereof. These and other such considerations are therefgre considered to fall within the scope of the present disclosure. Upon completion of the selected cooling cycle, the regeneration cycle ends at step 710.
[0047] In any of the above cases, and with reference again to Figures 1 to 4, once the cooling cycle has been completed, the regeneration tower 102 is either isolated to preserve its dryness, or again used for processing, whereby the processing tower 104 may then be itself regenerated, with appropriate reversal of the system's diversion mechanisms.
[0048] For example, in one embodiment, the processing tower is brought offline for regeneration periodically, in accordance with a prescribed regeneration schedule. For example, regeneration may be prescribed every 8 or 12 hours such that each tower is operated as processing tower for half or a third of each day, such as may be the case in a processing plant operated around the clock. In another embodiment, however, the processing tower may be operated as such as long as its operating conditions meet certain requirements. For instance, in one example, a dew point monitor is operated at the inlet and/or outlet of the processing tower so to monitor a humidity level thereof.
In such system, the processing tower may remain online as long as the dew point (humidity) of the process gas does not go above a certain degree, at which point a regeneration cycle is HON-ADO/CDA
initiated. Using this approach, regeneration is only applied when needed, thus increasing an overall efficiency of the system.
[0049] In another embodiment, the regeneration cycle initiation may rather be selected as a function of a number of parameters, for example including, but not limited to, process gas inlet dew point, process gas outlet dew point, ambient air dew point, process duration, etc. For example, with reference to Figure 8, and in accordance with one embodiment of the invention, a control sequence implemented by a controller of a desiccant drying system in selecting when to initiate a regeneration cycle is schematically illustrated. In this embodiment, a processing cycle is initiated at step 802.
During this to process, the controller monitors a process dew point (803) for comparison with a preset threshold therefor. Upon identifying at decision step 804 that the process dew point exceeds its threshold, regeneration is automatically initiated at step 806.
[0050] At the same time, the controller monitors a processing time or duration for this cycle and, until this time exceeds a preset threshold therefor at decision step 808, the process continues unimpeded. Once the duration exceeds its threshold, however, and prior to the process dew point exceeding its threshold, the controller accesses a current ambient air dew point (809) at decision step 810 and, should this ambient dew point exceed a preset threshold therefor, regeneration is initiated at step 806.
Otherwise, the process continues until either the process dew point 803 or the ambient dew point 809 exceeds its respective threshold, as determined at decision step 812. Applying this delayed approach to regeneration initiation, as will be demonstrated in the following examples, allows for significant energy savings as regeneration is only implemented when deemed necessary and energetically favourable.
[0051] As will be appreciated by the skilled artisan, additional system components may be considered in the present context to further assist in the control and redirection of gas flows within the system. For example, cutoff valves may be used at different locations within the system to isolate certain components of the system, namely, the regeneration tower once the regeneration cycle has been completed, or again both towers HON-ADO/CDA
in the event the entire system is shutoff, so to preserve the dryness of the desiccant between uses. Similarly, while a single ambient air inlet has been depicted in providing ambient air for both ambient air heating and cooling, distinct ambient air inlets may also be contemplated, as can different ambient air sources be considered (e.g.
outside air, air from within a processing plant or establishment where the system is being operated, etc.).
Also, while no specific mention is made in the above-referenced figures as to where and how the regeneration air may be used upon exiting the regeneration tower, it will be appreciated that the moist air thus provided may be used, for example, in heating and humidifying the establishment in which the system is operated, for certain processes where warm moist air may be of use, processed through a heat exchanger to recuperate heat energy therefrom, or again simply released outside.
[0052] With reference to Figure 5, a controller, generally referred to using the numeral 200, and in accordance with one embodiment of the invention, will now be described. In this embodiment, the controller is configured to have access to ambient air dew point data from an internal or external dew point monitor (or sensor), and control operation of at least some of the system's various gas diversion mechanisms in response thereto. For instance, the controller, as described above, may be configured to select from a series of preset regeneration cooling cycles, a cooling cycle associated with a current ambient air dew point, thus improving system performance characteristics. The controller may also, or alternatively, select when to implement a new regeneration cycle based, in part, on the detected ambient air dew point. These options are described in greater detail above with reference to Figures I to 4 and 6 to 8, and below with reference to the following examples.
[0053] In this illustrative embodiment, the controller is diagrammatically depicted to comprise a power supply 202 (e.g. line and/or battery power source), an input/output 204 (e.g. for input of control parameters, cycle data/parameters, system updates, etc., and output of performance data, past/current/upcoming cycle parameters, version code, status, etc.), and user interface 210, which may include an integrated, local and/or remote is HON-ADOICDA.
interface for user interaction with the system's control protocols and/or data. The controller further comprises one or more computer-readable media 208 for storing preset cooling cycles, system operation controls, regeneration initiation protocols, and the like, and one or more processors 206 for implementing same. As will be appreciated by the skilled artisan, the controller 200 may take various forms such as a dedicated system specific computing device, a programmed general purpose computing device (e.g.
desktop, laptop, etc.), or other such self-standing computing platform, or again consist or form part of a system control module implemented within the context of a larger system or plant-wide computer control platform, or the like. These and other such considerations to will be apparent to the person of ordinary skill in the art, and should therefore be considered to fall within the scope of the present disclosure.
[0054] Reference will now be made to the following non-limiting examples, in which sample results are provided with respect to exemplary embodiments of the invention.
Example 1 [0055] The following provides an example of preset ambient air cooling periods selected as a function of ambient air dew point, thus providing for increased system performance and efficiency in implementing a regeneration cycle, in accordance with one embodiment of the invention.
[0056] In this particular example, a process air outlet dew point threshold was set at -15 F. In the event that the process air outlet dew point exceeded this threshold, regeneration was initiated immediately. Unless this threshold was reached, however, regeneration was only initiated in the event that more than 8 hours had passed since the last regeneration and that the ambient air dew point was greater than -5 C .
Using this approach, the desiccant life is extended while regeneration cycles and times could be reduced as well as energy consumption by the heaters and blowers.
HON-ADO/CDA
[0057] Once the regeneration is initiated, the regenerating tower is first exposed to a heating cycle lasting approximately 140 minutes (heated ambient air), followed by a cooling cycle selected as a function of detected ambient dew point. Namely, the cooling cycle in this example consisted of a precooling period of ambient air cooling, followed by process air cooling period. The table below provides different precooling period durations as a function of detected ambient air dew point temperature ranges, which allows for a reduction in the usage of expensive dry air during the cooling phase. In one embodiment, specific cooling periods may be adjusted by way of a PID controller or the like, thus {
providing greater improvements in system control and performance.
to Outside Air Dew point Pre cool minute temperature C (ambient air) <-10 85 -lO to 0 75 0 to 5 45 5 to 10 35 >15 25 [0058] In this example, if one considers a total cooling period of approximately 2 hours, the ambient air cooling period will consist of between 20% and 70% of this total cooling period, depending on ambient air dew point, thus representing in even the worst of cases, a significant reduction in process air cooling and losses.
Example 2 [0059] The following provides some observed performance parameters in implementing some of the above improvements, in accordance with some embodiments of the invention.
[0060] In a first test, the process air set point was adjusted to approximately -15F
from -40F, and the controller was set to only implement regeneration upon the set point being reached, or upon more than 8 hours passing since the last regeneration and the outside air reaching a dew point above -5 C. For example, when sourcing or replenishing HON-ADOICDA
process gas from an ambient air source, namely via one or more gas conditioning means such as compressors, heaters, exchangers and the like, for example, the load imposed on the conditioning means and/or desiccant will be significantly lessened when the dew point of this ambient air source is lower, thus delaying the need for regeneration.
Alternatively, when the dew point of the process air source becomes higher, it may become energetically favourable to regenerate the desiccant more regularly given the increased load thereon and/or process gas conditioning means. Using these parameters during the cold winter months in Canadian plants, it was observed that on average, two regenerations were saved every week on all dryers, resulting for this particular test in a combined power savings in the order of 70,000KWh.
[0061] Furthermore, upon discharging heating air into the plant rather than outside, a heating gas savings of approximately 25,500 cubic meters was observed.
[0062] Also, upon applying mixed air cooling consistent with the preset values listed above, compressed process air savings in the order of 96,000,000 cubic feet were observed, resulting in power savings in the order of 350,000KWh.
[0063] While extra energy was expended in running the blowers during ambient air cooling, overall, power savings in the order to 400,000KWh where observed.
[0064] While the present disclosure describes various exemplary embodiments, the disclosure is not so limited. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
HON-ADO/CDA
Claims (34)
1. A desiccant drying system, comprising:
at least two desiccant chambers;
an ambient air dew point monitor;
multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to:
divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber, a composition of said cooling air being selectively adjusted via controller operation of said multiple air diversion mechanisms responsive to said ambient air dew point monitor.
at least two desiccant chambers;
an ambient air dew point monitor;
multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to:
divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber, a composition of said cooling air being selectively adjusted via controller operation of said multiple air diversion mechanisms responsive to said ambient air dew point monitor.
2. The system of claim 1, wherein said cooling air composition is selectively adjusted to provide an ambient air cooling period and a subsequent dried process air cooling period predetermined as a function of ambient air dew point.
3. The system of claim 2, wherein said ambient air cooling period is selected between 0% and 100% of a total cooling period.
4. The system of claim 3, wherein said ambient air cooling period is selected between 20% and 70% of a total cooling period.
5. The system of claim 1, wherein said cooling air composition comprises a predetermined ratio of cooling ambient air to cooling dried process air selected as a function of ambient air dew point.
6. The system of claim 5, wherein said cooling ambient air and said cooling dried process air are directed simultaneously through the regeneration chamber in accordance with said ratio.
7. The system of claim 5, wherein said cooling ambient air and said cooling dried process air are directed sequentially through the regeneration chamber in accordance with said ratio.
8. The system of claim 1, said multiple ambient air channeling mechanisms comprising an ambient air inlet and heater selectively activated responsive to said controller, wherein said heated ambient air and said cooling ambient air are both provided via said ambient air inlet upon said controller respectively activating and deactivating said heater.
9. The system of any one of claims 1 to 8, further comprising a dried process air dew point monitor, said controller alternating operation of said at least two desiccant chambers for processing and regeneration as a function of both a monitored dried process air dew point and said monitored ambient air dew point, wherein regeneration is only initiated upon said dried process air dew point exceeding a preset threshold therefor, or prior thereto but beyond a preset process duration threshold, upon said ambient air dew point exceeding a preset threshold therefor.
10. The system of any one of claims 1 to 9, wherein said composition is selected in accordance with a selected one of a series of preset regeneration cooling cycles, each one of which associated with a respective ambient dew point range.
11. A desiccant drying system, comprising:
at least two desiccant chambers;
an ambient air dew point monitor;
multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to:
divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber in accordance with one of at least two preset regeneration cooling cycles selected by said controller responsive to said ambient air dew point monitor, at least one of said preset regeneration cooling cycles comprising ambient air cooling.
at least two desiccant chambers;
an ambient air dew point monitor;
multiple ambient and process air channeling and diversion mechanisms; and a controller for controlling said multiple diversion mechanisms in alternating operation of said at least two desiccant chambers for processing and regeneration, wherein said multiple air diversion mechanisms are operable by said controller to:
divert process air through a processing one of said at least two desiccant chambers to be dried thereby, and divert regeneration air through a regeneration one of said at least two desiccant chambers for regeneration, wherein said multiple diversion mechanisms are operated to direct heated ambient air through the regeneration chamber, and subsequently direct cooling air through the regeneration chamber in accordance with one of at least two preset regeneration cooling cycles selected by said controller responsive to said ambient air dew point monitor, at least one of said preset regeneration cooling cycles comprising ambient air cooling.
12. The system of claim 11, said ambient air cooling comprising at least one of a distinct ambient air cooling period and a combined ambient and dried process air cooling period.
13. A method for regenerating desiccant of a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of:
detecting an ambient air dew point;
heating the desiccant with heated ambient air;
selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
detecting an ambient air dew point;
heating the desiccant with heated ambient air;
selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
14. The method of claim 13, wherein said ambient air cooling comprises at least one of a distinct ambient air cooling period and a combined ambient and dried process air cooling period.
15. The method of claim 13, wherein said at least one of said preset desiccant cooling cycles comprises:
cooling the desiccant with cooling ambient air for a predetermined ambient air cooling period; and subsequently cooling the desiccant with dried process air for a predetermined process air cooling period;
wherein at least one of said predetermined ambient air cooling period and said predetermined dried process air cooling period is selected as a function of said detected ambient air dew point.
cooling the desiccant with cooling ambient air for a predetermined ambient air cooling period; and subsequently cooling the desiccant with dried process air for a predetermined process air cooling period;
wherein at least one of said predetermined ambient air cooling period and said predetermined dried process air cooling period is selected as a function of said detected ambient air dew point.
16. The method of claim 15, wherein said predetermined ambient air cooling period is selected between 0% and 100% of a total cooling period.
17. The method of claim 16, wherein, when said detected ambient air dew point is below a predetermined lower threshold, said predetermined ambient air cooling period consists of 100% of said total cooling period and said dried process air cooling period consists of 0% of said total cooling period.
18. The method of claim 16 or 17, wherein, when said detected ambient air dew point is above a predetermined higher threshold, said predetermined ambient air cooling period consists of 0% of said total cooling period and said dried process air cooling period consists of 100% of said total cooling period.
19. The method of claim 16, wherein said predetermined ambient air cooling period is selected between 20% and 70% of the total cooling period.
20. The method of claim 13, wherein said at least one of said preset desiccant cooling cycles comprises simultaneously cooling the desiccant with ambient air and dried process air in accordance with a predetermined ratio associated with said detected ambient air dew point.
21. The method of any one of claims 13 to 20, wherein said heated ambient air is subsequently recycled via one or more of a heat exchanger for recuperating heat therefrom and recirculation through a building for heating and humidifying same.
22. The method of any one of claims 13 to 21, wherein each of said at least two preset desiccant cooling cycles is associated with a preset ambient air dew point range.
23. The method of any one of claims 13 to 22, further comprising the step of delaying initiation of the regeneration cycle as a function of the detected ambient air dew point.
24. The method of claim 23, said delaying step comprising:
comparing a detected dried process gas dew point with a preset process dew point threshold and delaying initiation of the regeneration cycle until the detected process gas dew point exceeds said preset process dew point threshold; and beyond a preset process duration threshold and prior to the detected dried process gas dew point exceeding said preset process dew point threshold, comparing the detected ambient air dew point with a preset ambient dew point threshold and initiating the regeneration process upon said detected ambient air dew point exceeding said preset ambient threshold.
comparing a detected dried process gas dew point with a preset process dew point threshold and delaying initiation of the regeneration cycle until the detected process gas dew point exceeds said preset process dew point threshold; and beyond a preset process duration threshold and prior to the detected dried process gas dew point exceeding said preset process dew point threshold, comparing the detected ambient air dew point with a preset ambient dew point threshold and initiating the regeneration process upon said detected ambient air dew point exceeding said preset ambient threshold.
25. The method of any one of claims 13 to 24, implemented by a controller operatively coupled to the drying system and comprising a processor operatively coupled to a computer-readable medium having encoded therein each of said preset desiccant cooling cycles, and having further encoded therein statements and instructions that, upon implementation by said processor, controls implementation of desiccant regeneration.
26. A computer-readable medium having encoded therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to control implementation of a regeneration cycle for a given desiccant chamber thereof as a function of a detected ambient air dew point by:
directing heated ambient air through the given desiccant chamber;
selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
directing heated ambient air through the given desiccant chamber;
selecting one of at least two preset desiccant cooling cycles as a function of said detected ambient air dew point, at least one of said preset desiccant cooling cycles comprising ambient air cooling; and cooling the desiccant in accordance with said selected preset desiccant cooling cycle.
27. The computer-readable medium of claim 26, having further encoded therein said at least two preset desiccant cooling cycles, each one of which associated with a preset ambient dew point range, and having further encoded therein statement and instructions for comparing said detected ambient air dew point with each said preset ambient dew point range in selecting said one of said at least two preset desiccant cooling cycles.
28. The computer-readable medium of claim 26, having further encoded therein statements and instructions for delaying initiation of the regeneration cycle as a function of the detected ambient air dew point.
29. The computer-readable medium of claim 28, further for controlling initiation of the regeneration cycle as a function of a detected dried process gas dew point and having encoded therein statements and instructions for:
comparing the detected dried process gas dew point with a preset process dew point threshold and delaying initiating the regeneration process until the detected process gas dew point exceeds said preset process dew point threshold; and beyond a preset process duration threshold and prior to the detected dried process gas dew point exceeding said preset process dew point threshold, comparing the detected ambient air dew point with a preset ambient dew point threshold and initiating the regeneration process upon said detected ambient air dew point exceeding said preset ambient threshold.
comparing the detected dried process gas dew point with a preset process dew point threshold and delaying initiating the regeneration process until the detected process gas dew point exceeds said preset process dew point threshold; and beyond a preset process duration threshold and prior to the detected dried process gas dew point exceeding said preset process dew point threshold, comparing the detected ambient air dew point with a preset ambient dew point threshold and initiating the regeneration process upon said detected ambient air dew point exceeding said preset ambient threshold.
30. A method for automatically selecting when to initiate a desiccant regeneration cycle for a given desiccant chamber in a multiple desiccant chamber drying system, the method comprising the steps of:
monitoring a process duration and a process gas dew point for the given desiccant chamber in operation, and an ambient air dew point;
comparing said process gas dew point with a preset process dew point threshold;
initiating regeneration upon said detected process gas dew point exceeding said preset process threshold;
upon said process duration exceeding a preset process duration threshold and prior to said process gas dew point exceeding said preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold.
monitoring a process duration and a process gas dew point for the given desiccant chamber in operation, and an ambient air dew point;
comparing said process gas dew point with a preset process dew point threshold;
initiating regeneration upon said detected process gas dew point exceeding said preset process threshold;
upon said process duration exceeding a preset process duration threshold and prior to said process gas dew point exceeding said preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of the regeneration cycle until said ambient air dew point exceeds said preset ambient dew point threshold.
31. The method of claim 30, said monitoring step comprising monitoring a dried process gas dew point of a dried process gas exiting the given desiccant chamber in operation.
32. A method for extending a desiccant drying cycle beyond a preset process duration threshold in a multiple desiccant chamber drying system, the method comprising the steps of:
monitoring a process duration, a dew point of a process gas dried by a desiccant and an ambient air dew point;
upon said process duration exceeding the preset process duration threshold and prior to said process gas dew point exceeding a preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of a regeneration cycle for said desiccant until said ambient air dew point exceeds said preset ambient dew point threshold.
monitoring a process duration, a dew point of a process gas dried by a desiccant and an ambient air dew point;
upon said process duration exceeding the preset process duration threshold and prior to said process gas dew point exceeding a preset process dew point threshold, comparing said ambient air dew point with a preset ambient dew point threshold; and delaying initiation of a regeneration cycle for said desiccant until said ambient air dew point exceeds said preset ambient dew point threshold.
33. A computer-readable medium having encoded therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the method of claim 30 or claim 31.
34. A computer-readable medium having encoded therein statements and instructions for implementation by a processor of a multiple desiccant chamber drying system to implement the method of claim 32.
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| CA2732541A CA2732541C (en) | 2011-02-23 | 2011-02-23 | Desiccant drying system and method of operation thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014099738A3 (en) * | 2012-12-18 | 2015-07-16 | Waukesha Electric Systems, Inc. | Dehumidifier and breather for operation during regeneration |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104567328B (en) * | 2014-12-29 | 2016-08-24 | 青岛市华测检测技术有限公司 | Drying bottle blast apparatus |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014099738A3 (en) * | 2012-12-18 | 2015-07-16 | Waukesha Electric Systems, Inc. | Dehumidifier and breather for operation during regeneration |
| US9114353B2 (en) | 2012-12-18 | 2015-08-25 | Waukesha Electric Systems, Inc. | Dehumidifier and breather configured for operation during regeneration |
| US10086327B2 (en) | 2012-12-18 | 2018-10-02 | Spx Transformer Solutions, Inc. | Dehumidifier and breather configured for operation during regeneration |
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| CA2732541C (en) | 2014-08-26 |
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