Abstract:
Methods and apparatuses are provided for separating froth into liquid and gas components. One apparatus includes a container that is configured to hold froth therein and change at least a portion of the froth into substantially separate liquid and gas portions when an electrostatic charge is discharged through at least a portion of the froth between at least two electrodes at least partially arranged within the container.

Description:
BACKGROUND  
       [0001]     Certain devices that move or otherwise handle liquid(s) may produce froth. Froth, for example, can occur when the liquid(s) mix with gas to form bubbles. A build-up of such bubbles can lead to a layer of froth on top of the liquid. In certain instances gas maybe drawn into the liquid resulting in froth. In other instances gas may be drawn or otherwise released from within the liquid resulting in froth.  
         [0002]     Froth will usually return to separate liquid and gas components, but this can take a significant amount of time and possibly also space to hold the froth as it slowly separates. Such time and or space are often unacceptable for certain devices or processes. Thus, to avoid froth or otherwise reduce the volume of froth produced, special chemicals or compounds are often added to the liquid that tend to reduce or eliminate unwanted froth.  
         [0003]     However, there are some devices and processes that simply cannot accommodate such special chemicals or compounds. In other situations, the additional cost of such special chemicals or compounds may be prohibitive.  
         [0004]     Consequently, there is a need for methods and apparatuses for handling froth. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     The following detailed description refers to the accompanying figures.  
         [0006]      FIG. 1A  is an illustrative diagram depicting an exemplary fluid handling device having a container configured to handle froth in accordance with certain implementations of the present invention.  
         [0007]      FIG. 1B  is an illustrative diagram depicting an exemplary fluid handling device having a container configured to handle froth as in  FIG. 1A  further illustrating froth, and froth that has been separated into liquid and gas portions, in accordance with certain implementations of the present invention.  
         [0008]      FIG. 2  is an illustrative diagram depicting an exemplary printing device having a container configured to handle froth, in accordance with certain implementations of the present invention.  
         [0009]      FIG. 3  is flow diagram depicting a method for use with devices, for example, such as those illustrated in FIGS.  1 A-B, and  2 , for handling froth, in accordance with certain implementations of the present invention.  
         [0010]      FIG. 4  is a diagram depicting exemplary circuitry for applying an electrostatic charge, in accordance with certain implementations of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0011]     Attention is drawn to  FIG. 1A , which is an illustrative diagram depicting an exemplary fluid handling device  100  having a container  102  configured to handle froth in accordance with certain implementations of the present invention.  
         [0012]     As shown, fluid handling device  100  includes container  102  having, in this example, a housing  104  forming therein an opening  106  which is suitable for holding froth. Here, froth is introduced into opening  106  through a froth port  108 . Opening  106  further includes a liquid port  110  that allows liquid separated from the froth within opening  106  to exit container  102 . Opening  106  also includes a gas port  112  that allows gas separated from the froth within opening  106  to exit container  102 .  
         [0013]     In this embodiment, froth port  108  is fluidically coupled to a froth conduit  114  which is further fluidically coupled to a froth source  116 . Similarly, liquid port  110  is fluidically coupled to a liquid conduit  118  which is further fluidically coupled to a liquid destination  120 .  
         [0014]     In certain other implementations, all or some of the froth and liquid components may be combined. For example, froth port  108  and liquid port  110  may be combined into a single port that allows froth to enter into opening  106  and liquid to exit from within opening  106 . Froth conduit  114  and liquid conduit  118  may be similarly combined into one conduit that carries froth towards container  102  and liquid away from container  102 . In such examples and/or other implementations, froth source  116  and liquid destination  120  may also be combined as a single container or vessel that is configured to hold both liquid and froth. Such combinations are represented by connector  132  shown in dashed line format.  
         [0015]     With regard to the exemplary device in  FIG. 1A , a gas conduit  122  is fluidically coupled to gas port  112 . Here, gas may exit opening  106  and be released (e.g., vented) into the atmosphere as illustrated as gas destination  124   a  and/or collected or otherwise handled using a gas destination  124   b  fluidically coupled to gas port  112 . In certain implementations, gas port  112  may directly vent gas into the atmosphere without requiring gas conduit  122 . Gas port  112 , gas conduit  122  and/or gas destination  124   b  may be configured to reduce the chance for liquid or froth from escaping therethrough by including one or more controlling mechanisms as are well known in the art for reducing fluid leaks and the like. For example, in certain implementations, a gas-permeable filter (not shown) and/or a serpentine conduit shape (not shown) may be employed to hinder liquid movement.  
         [0016]     Circuitry  126  is shown as being connected to at least two electrodes that are at least partially arranged within opening  106 . In this example, circuitry  126  is configured to generate a voltage potential between an upper electrode  128   a  and a lower electrode  128   b,  which are separated by a gap space  130  within opening  106 . When applied by circuitry  126 , the voltage potential creates an electrostatic charge between the electrodes. This electrostatic charge is discharged through the froth located within opening  106 . The electrostatic discharge tends to reduce the amount of froth.  
         [0017]     The reduction of froth is believed to be caused by the electrostatic discharge creating localized heating of the bubble lamella, disrupting the surface tension and causing the bubble to rupture. The high temperature of the spark vaporizes the liquid faster than the surface tension can recover destabilizing the lamella.  
         [0018]     Those skilled in the art will recognize that circuitry  126  may take on several forms, as there are many well known circuits that may be employed to generate the voltage potential.  
         [0019]     By way of example, a simple charging/discharging circuit  400  is illustrated in  FIG. 4 . Circuit  400  may be included, for example, in circuitry  126 . Circuit  400  includes a DC voltage source  402  coupled to a charging resistor  404 . Charging resistor  404  is further coupled to a relay  406 . When relay  406  is in a first position the voltage potential from source  402  is applied to charge storage capacitor  408 . Capacitor  408  is then charged. Subsequently, when relay  406  is in a second position the capacitor  408  is allowed to discharge through a current limiting resistor  410  and through froth between the electrodes in container  102 . In one exemplary implementation, DC voltage source  402  outputs 8,000 volts, charging resistor  404  is a 1 MΩ resistor, charge storage capacitor  408  is a 100 pF capacitor, current limiting resistor is a 1 kΩ resistor, and the resulting electrostatic discharge is about 8,000 volts.  
         [0020]     Furthermore, those skilled in the art will recognize that the voltage potential will likely be different depending upon various design characteristics and the like. For example, the voltage potential may correspond in some manner to the arranged opening  106 , electrodes  128 , the gap space  130  (or gap spaces if more than two electrodes are used), certain properties or characteristics of the liquid and/or the gas, the amount of froth present or expected, etc. By way of example, in certain implementations a voltage potential of at least about 1,000 volts may be required, while in other implementations the requisite voltage potential may be lower or greater. In certain exemplary implementations such as that depicted in  FIG. 2 , for example, the voltage potential is typically between about 8,000 and about 12,000 volts.  
         [0021]     In certain implementations, circuitry  126  is configured to selectively apply the voltage potential when the volume of froth within opening  106  reaches or possibly exceeds a defined threshold froth volume level. Hence, circuitry  126  may include a monitoring mechanism  127  that senses the froth volume level or otherwise identifies the froth volume level in a manner that causes circuitry  126  to apply the voltage potential. Monitoring mechanism  127  may include, for example, electrical, mechanical, and/or optical based sensors or other like devices. Circuitry  126  may include logic and/or other mechanisms to respond to monitoring mechanism  127 . In certain implementations, circuitry  126  may be programmably configured and the threshold froth volume level(s) established.  
         [0022]     In certain implementations, circuitry  126  may be configured to apply the voltage potential periodically, perhaps in accordance with a desired schedule. For example, the voltage potential may be applied every ten seconds.  
         [0023]     Circuitry  126  may be configured to apply the voltage potential a plurality of times during a set period of time. For example, the voltage potential may be applied at a rate of once per second (i.e., 1 Hz). Such a rate may be higher or lower in other implementations. For example, a rate of about 20 Hz was found to be effective in certain implementations as for example in  FIG. 2 .  
         [0024]     Those skilled in the art will recognize also that circuitry  126  may be configured to apply different voltages at certain times, or upon different levels of froth, or through different electrodes, etc.  
         [0025]     Attention is now drawn to  FIG. 1B . Here, froth  134  is urged or otherwise allowed in some manner to travel from froth source  116  through froth conduit  114  and into opening  106 . An electrostatic discharge is illustrated by conductive path(s)  140  as passing between electrodes  128   a  and  128   b  through portions of froth  134 . The electrostatic discharge tends to separate at least some of froth  134  into liquid  136  and gas  138  portions. In this example, the separated liquid  136  descends within opening  106  following the electrostatic discharge where it may then be urged or otherwise allowed in some manner to travel from opening  106  through liquid conduit  118  and into liquid destination  120 . The separated gas  138  ascends within opening  106 , above any remaining froth  134  and/or liquid  136 , where it may then be urged or otherwise allowed in some manner to travel from opening  106  through gas conduit  122  and into a liquid destination  124   a  and/or  124   b.    
         [0026]     A threshold froth volume level  142  is illustrated in  FIG. 1B . As described above, in certain implementations, circuitry  126  may be configured to selectively apply the voltage potential provided that the froth volume level is at or above threshold froth volume level  142 . In other implementations, threshold froth volume level  142  may reflect the level at which there is simply enough froth  134  between electrodes  128   a - b  to cause the discharge via conductive path  140 .  
         [0027]      FIG. 2  is an illustrative diagram depicting an exemplary printing device  200  having a container  216  configured to handle froth, in accordance with certain further implementations of the present invention.  
         [0028]     Printing device  200  is a representative inkjet printing device. Printing device  200  includes a printhead  202  having one or more nozzles  204  configured to selectively eject droplets of fluid, such as for example, ink  214 . Printhead  202  is fluidically coupled to a printhead reservoir  206  that holds and supplies ink  214  to printhead  202 . Printhead reservoir  206  is further fluidically coupled through a conduit  208   a  to a pump  210 . In this example pump  210  is a bidirectional pump and is further fluidically coupled to an ink cartridge  212  through a conduit  208   b.  Ink cartridge  212  stores ink  214 . Pump  210  may be operated to selectively pump ink  214  from ink cartridge  212  to printhead reservoir  206 , or from printhead reservoir  206  to ink cartridge  212 . Froth may be created due to this pumping action and/or as a result of some other process or property. Thus, froth may accumulate in ink cartridge  212 .  
         [0029]     The froth in ink cartridge  212  is allowed to enter into container  216  via conduit  208   c.  Froth  134  within container  216  is then subjected to an electrostatic discharge and the separated ink is allowed to return to container  216  via conduit  208   c.  The separated gas is allowed to exit container  216  via gas port  112 .  
         [0030]     Although shown separately, in certain other implementations, ink cartridge  212  and container  216  may be combined to form a single vessel. Similarly, in still other implementations, ink cartridge  212 , container  216  and printhead reservoir  206  may be combined to form a single vessel.  
         [0031]      FIG. 3  is flow diagram depicting a method  300  for use with fluid handling devices, for example, such as those illustrated in  FIGS. 1 and 2 , for handling froth, in accordance with certain implementations of the present invention.  
         [0032]     In act  302  a threshold froth volume level  142  is established, for example, as described in the examples above or in other ways. In act  304  an electrostatic charge is applied by circuitry  126  to electrodes  128 . In act  306  the froth discharges the electrostatic charge when the froth reaches the threshold froth volume level  142 . Acts  304  and  306  may then be repeated.  
         [0033]     In a second exemplary method, as depicted with dashed lines in  FIG. 3 , in act  308  the froth volume level may be measured. In act  310 , when the measured froth volume level reaches the threshold froth volume level  142 , circuitry  126  applies the electrostatic charge that then discharges through froth  134 . Acts  308  and  310  may then be repeated.  
         [0034]     Although the above disclosure has been described in language specific to structural/functional features and/or methodological acts, it is to be understood that the appended claims are not limited to the specific features or acts described. Rather, the specific features and acts are exemplary forms of implementing this disclosure.