WO2008091845A1

WO2008091845A1 - A water treatment system and process for a variable water flow rate and filter life monitoring algorithm and system

Info

Publication number: WO2008091845A1
Application number: PCT/US2008/051624
Authority: WO
Inventors: James Doyle; James Larson; David Bardwell
Original assignee: Ecowater Systems LLC
Current assignee: Ecowater Systems LLC
Priority date: 2007-01-22
Filing date: 2008-01-22
Publication date: 2008-07-31
Anticipated expiration: 2009-07-22

Abstract

In a point-of-entry water treatment system having a large granular activated carbon filter, approximately 80% of residential water usage is of a relatively low flow rate. A replaceable carbon pre-filter is added to filter the low flow rate, thus significantly extending the life of the large GAC filter. In addition, the flow rate is monitored and the remaining filter capacity of the pre-filter is calculated and displayed to a user. In another embodiment, the pre-filter and filter monitor are incorporated in other water treatment systems.

Description

A WATER TREATMENT SYSTEM AND PROCESS FOR A VARIABLE

WATER FLOW RATE AND FILTER LIFE MONITORING

ALGORITHM AND SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Application No. 60/885,999,

filed January 22, 2007.

FIELD OF THE INVENTION

The present invention relates to water treatment systems and, in particular, point- of-entry water treatment systems subject to variable water flow rate demands.

BACKGROUND OF THE INVENTION

The prior art includes filter tanks for use in residential and commercial use. In particular, the prior art includes point-of-entry (POE) filter tanks. The filter tank has a finite life of typically 2-4 years, dependent on the water usage. At the end of the filter tank life, the filter tank must be replaced. The filter tank is a large and expensive item which is not readily replaced.

The prior art also includes a dual carbon filter used in a low flow rate system, such as an under counter point-of-use (POU) products.

SUMMARY OF THE INVENTION

The present invention recognizes and takes advantage of the fact that approximately 80% of residential water usage is of a relatively low flow rate, such as required by a coffee machine, ice maker, bathroom faucet, and drinking water dispenser. Attorney Docket No: 223644-001301

Conversely, approximately 20% of the water flow rate is a relatively high flow rate, such as a clothes washing machine or simultaneous shower usage, toilet flushing and the filling of a pot, for example. For example, low flow rate may be in the range of 2 to 3 gallons of water per minute. 10 gallons per minute is considered in many systems to be in the high flow rate range. Of course, the present invention is not limited to residential systems.

The present invention is directed particularly to POE water treatment systems subject to variable water flow rate demands. The present invention provides a small carbon pre-filter cartridge with high physical flow capability at low pressure drop fluidly coupled to a large granulated activated carbon (GAC) bed filter. The pre-filter has an inlet coupled to the source of the influent water. The outlet is coupled to the inlet of the larger carbon filter. The outlet of the larger filter provides the effluent water. The pre- filter provides a water treatment contact time which is adequate only for lower flow rates, and quickly becomes overrun by higher flow rates. The larger filter provides water treatment contact time which is capable of filtering various contaminants, such as arsenic, lead and chlorine, for example, from water having a high flow rate, as well as low flow rates. As a result, the pre-filter will be capable of filtering approximately 80% of the water demand, prior to the water passing through the larger filter, to protect the main bed of the large filter from peak volatile organic chemicals (VOC)/TOC/chlorine or other contaminants. In the event of a high flow rate, the water will pass through the pre-filter with inadequate filtering, and then through the larger filter which will be capable of filtering the water having a high flow rate. Thus, the larger filter will be called upon for Attorney Docket No: 223644-001301

filtering approximately 20% of the water demand, thus significantly extending the life of the large filter. The pre-filter will be mechanically designed to readily accommodate periodic replacement by the end user. It is anticipated that the pre-filter will be replaced approximately every 6 months. Of course, replacement time of the pre-filter will vary dependent on various factors, including contact time of the pre-filter, the size of the pre- filter, and the water flow rate and time of water flow.

The present invention also provides a method and system of monitoring carbon life of the pre-filter. The system will include a means for monitoring the rate of flow, such as a flow rate meter. The output of the flow rate meter will be coupled to a controller having a indicator to indicate the anticipated replacement period of the pre- filter.

In particular, the present invention provides a means for extending the service life of a POE carbon tank filter. The main carbon bed is protected at lower flow rates by a replaceable pre-filter. The actual system's varying flow rate will be monitored to predict filter end point. Testing will be done to determine pre-filter 2 ppm chlorine removal at 1 , 2, 3, 4, 5, and 6 gpm and will be referenced in the controller. At the different flow rates, the filter will have different capacities. This algorithm will account for the different capacities and percentage of chlorine removed at the various flow rates. This will allow the system to accurately predict the chlorine removal end point of the pre-filter.

For example, at 1 gpm the filter will have a chlorine removal capacity of 10,000 gallons and 100% of the chlorine will be removed. At 4 gpm the filter will have 7,000 Attorney Docket No: 223644-001301

gallons of life and 70% of the chlorine will be removed. At 6 gpm the filter will have 5,000 gallons capacity and 50% of the chlorine will be removed. As the system operates in the field, low flows of 1 gpm will be tallied as 2 ppm per gallon of chlorine removal, as flow increases to say 6 gpm only 1 ppm of the chlorine is removed by the pre-filter and will be tallied as such. The algorithm will also account for the removal capacity based on average flow rate through the system. A system with a lower average flow rate, i.e. 2 gpm, will consume more of the pre-filter' s capacity than a system that runs at a higher average flow rate, i.e. 5 gpm.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure l is a schematic block diagram of a POE carbon filter system in accordance with one embodiment of the present invention.

Figure 2 is a functional flow chart of the process for determining the remaining capacity of the pre-filter of the present invention.

Figure 3 is an illustrative example of an algorithm or table of data for determining the remaining capacity of the pre-filter of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 is a schematic block diagram of a POE filter system 10 in accordance with one embodiment of the present invention. While the embodiments disclosed are shown principally as a carbon filter system, it will be appreciated that the present invention is also applicable to other systems, such as for arsenic removal, sediment Attorney Docket No: 223644-001301

removal, and an ion exchange resin system, for example. The POE carbon filter system 10 includes a main carbon filter 12. The main carbon filter 12 may be a granular activated carbon (GAC) filter. In the embodiment shown in Figure 1 , the carbon filter 12 includes a tank 14, GAC 16, pipe 18, a conventional liquid perforated lower collector 20, and a conventional liquid perforated upper distributor 22. The tank 14 is shown to be of a size 8 inch by 25 inch. However, the invention is not intended to be limited to any one size. The pipe 18 includes a lower portion 24 and an upper portion 26. The lower portion 24 is coupled to the lower collector 20. The upper portion 26 is coupled to the upper distributor 22. The upper distributor 22 and upper portion 26 of the pipe 18 form an outlet port 28. The upper distributor 22 also includes inlet port 30.

Figure 1 shows a rotary flow control valve 32. Such control valves 32 are often incorporated in water treatment systems, such as shown in U.S. Patent No. 5,162,080, issued to Drager et al., and which is incorporated herein by reference. The patent shows a control valve coupled to a conventional liquid perforated upper distributor. The upper distributor is coupled via a pipe to a conventional liquid perforated collector.

Typically a rotary control valve 32 is utilized in a water softener system. It should be noted the present invention may be practiced in an application with our without a water softener. Further, the present invention may be practiced with or without a control valve. 32. Still further, other embodiments of the main carbon filter 12 are anticipated, such as one skilled in the art will appreciate. For the sake of convenience, Figure 1 shows the main carbon filter 12 coupled to the control valve 32 via conduits 34, 36. In Attorney Docket No: 223644-001301

particular, conduit 34 is coupled between inlet port 30 and valve exit port 38. Conduit 36 is coupled between outlet port 28 and valve input port 40. However, it will be appreciated that the conduits 34, 36 may be incorporated in the control valve 32 and filter 12.

Figure 1 further shows a replaceable pre-fϊlter 42. The pre-filter 42 includes an input port 44 and an output port 46. In one embodiment, the pre-filter 42 may be an encapsulated pre-filter. However, in another embodiment the pre-filter 42 may also be an open sump pre-filter. The input port 44 is coupled to the source or influent water 48. The output port 46 is coupled to the valve inlet port 50. The rotary control valve 32 includes a position which couples valve inlet port 50 to valve outlet port 38. As noted above, valve outlet port 38 is coupled via conduit 34 to the inlet port 30. The outlet port 28 provides effluent or treated water via the conduit 36 to the valve inlet port 40. The rotary control valve 32 includes a position which couples the valve inlet port 40 to the valve outlet port 52. The valve outlet port 52 provides the effluent or treated water to the system output 54. As suggested above, in another embodiment, the rotary control valve 32 may be omitted and the encapsulated pre-filter 42 is coupled directly to the main carbon filter 12.

A flow meter 56 is shown coupled to the valve outlet port 52. The flow meter 56 monitors the flow of fluid out of the valve outlet port 52. The flow meter 56 develops a signal representing the rate of flow at a flow meter output 58. The rotary control valve 32 includes a position switch 60 having a output 62 which generates a signal representing movement or position of the rotor (not shown) of the rotary control valve 32. The rotary Attorney Docket No: 223644-001301

control valve 32 includes a motor 64 which is coupled to the rotor. The motor 64 includes motor control inputs 66 which control operation of the motor 64.

Figure 1 also shows a controller unit 68. The controller unit 68 includes a memory 70 having a program for controlling a controller 71 , a display 72 for displaying data to a user, a user interface 74 which may include buttons or switches, for example, for controlling or inputting data to the controller unit 68. Further, the controller unit 68 includes a treated water flow input 76, a valve position switch input 78, and a valve motor control output 80.

The flow meter output 58 is coupled to the treated water flow input 76 via line 82. The position switch output 62 is coupled to the valve position switch input 78 via a line 84. The valve motor control output 80 is coupled to the motor control inputs 66 via lines 86.

Under control of the program in the memory 70, the control unit 68 controls the position of the motor 64 by developing the appropriate signals to the motor 64. The control unit 68 also verifies the position of the valve rotor 32 via the signal received from the position switch 60. Further, the control unit 68 monitors the flow of treated water. In addition, a user may program the control unit 68 via the user interface 74 to indicate that the pre-filter 42 has been replaced. Optionally, the user may indicate the model or type of pre-filter 42. Based on the user programmed data, the control unit 68 may calculate an anticipated performance life of the pre-filter 42 based on total treated water, and optionally, based in part on the programmed quality of the influent or supply water. Attorney Docket No: 223644-001301

Alternatively, the anticipated performance life of the pre-filter 42 may be preprogrammed or determined. As a result, the controller unit 68 is capable of estimating the value of the remaining performance life of the pre-filter 42. The value may be displayed by the user display 72. As a result, the user will anticipate the time period for replacing the pre-filter 42. It will be appreciated that various types of signals my be presented to indicate the need for replacement, such as numeric values, an illuminated color, series of blinking lights, or even an audible indication. Once the pre-filter 42 has been replaced, the user may again program the controller 71 to indicate the pre-filter 42 has been replaced.

It will be appreciated from the above that if the rotary control valve 32 is not included, it will still be advantageous to include a flow meter 56. The flow meter 56 provides the benefit of tracking the amount of water filtered by the pre-filter 42. Thus, the system 10 is capable of monitoring the pre-filter 42 performance life and providing an indication to the user.

In particular, the present invention provides a means for extending the service life of the POE main carbon filter 12. The main carbon filter 12 is protected at lower flow rates by the replaceable encapsulated pre-filter 42. As noted above, for each sized replaceable encapsulated pre-filter 42, an algorithm or table is created based on evaluation testing. The testing determines the amount of chlorine (e.g., typically in parts- per-million) which the pre-filter 42 is capable of filtering at various flow rates (e.g., 1 gpm through 6 gpm, for example). The capacity in gallons is determined at the various Attorney Docket No: 223644-001301

flow rates. Therefore, as the flow meter 56 monitors system water usage, preferably in terms of (N) gpm and the period of time (t) of the water flow at (N) gpm, the system is capable of determining the percentage of carbon life remaining in the pre-filter 42.

Figure 2 is a functional flow chart of the process for determining the remaining capacity of the pre-filter 42 in accordance with one embodiment of the present invention. Step 1 consists of installing a new water treatment system 10 and initializing the software in memory 70. Step 2 consists of setting the anticipated chlorine level which the system 10 is expected to treat. Of course, this value may also be pre-programmed into the control unit 68. Step 3 includes storing the algorithm in the control unit 68 for the specific pre- filter 42. Again, this step may be pre-programmed into the control unit 68. Alternatively, this step may follow and be included in step 4. Step 4 consists of installing a new pre- filter 42 and providing notification to the control unit 68 of the new pre-filter 42. Step 5 consists of the control unit 68 resetting the carbon filter performance capacity to 100%. Step 6 includes the flow meter 56 and control unit 68 detecting water flow. Step 7 includes determining the flow rate value (N) in gpm. Step 8 includes determining the time (t) of the water flow at (N) gpm. Step 9 includes calculating the percentage of the remaining capacity of the pre-filter 42. Step 10 includes displaying the capacity percentage to the user.

Referring back to Figure 1, the control unit 68 is shown to include a transceiver 90. A remote device 92 is also shown and includes a transceiver 94, controller 96 and display 98. It will be appreciate that the capacity percentage may be displayed remotely. Attorney Docket No: 223644-001301

The system 10 may be similar to U.S. Patent 6,456,202, which is incorporated herein by reference.

It should be noted that the use of the pre-filter 42 may impose a pressure differential across the pre-filter 42. The pressure differential will create a back pressure, particularly the higher the flow rate. Known filter design practices minimize the pressure differential and consequently the back pressure. For example, in one embodiment, the pre-filter 42 may include sintering carbon particles with a polymeric binder. U.S. Patent 7,022,274, issued to Harris et al and assigned to Graver Technologies, LLC, and incorporated herein by reference, discloses a gas sintered carbon block and method. In another design practice, the pre-filter 42 is constructed using concentric meshed cylindrical filter walls. Between the walls is a annular ring of carbon material. The thickness and general size of the carbon material may be selected as desired. In both embodiments, it will be appreciated that the construction of the pre-filter 42 may be dictated with the goal of reducing pressure differential at high flow rates.

Figure 1 shows a further optional feature, namely bypass device 100. The bypass device 100 includes an input port 102 coupled to the input port 44 of the pre-filter 42 and an output port 104 coupled to the output port 46 of the pre-filter 42. In one embodiment, the bypass device 100 is a poppet valve bypass device. The poppet valve is designed to open at a specified back pressure, thereby allowing flow through the bypass device 100 and to bypass the pre-filter 42. Thus, the bypass device 100 significantly reduces pressure differential and back pressure when the filter back pressure is at or over the specified Attorney Docket No: 223644-001301

filter back pressure. It will be appreciated that in the event a bypass device 100 is incorporated, the amount of flow of water which is bypassed from the pre-filter 42 must be factored into the algorithm or table. Such bypassing will tend to extend the life of the pre-filter 42 and must be considered for calculating the remaining performance capacity of the pre-filter 42.

The bypass device 100 allows greater system design flexibility. For example, having a bypass device 100 allows the design of a pre-filter 42 which is more efficient at filtering at low flow rates, e.g., the water flow rate of approximately 80% of the water flow system demand. However, the greater efficiency requires a pre-filter having a greater back pressure. The increased back pressure reduces system flow performance. The specified back pressure, at which the bypass device 100 opens, may be strategically selected to optimize the range of filtering performed by the pre-filter 42, yet allow the system to bypass the pre-filter 42 to avoid significant degradation in the system flow performance.

Figure 3 is an illustrative example of an algorithm or table 106. The table 106 is for a hypothetical pre-filter A and includes example data 108 which represents data obtained through testing or calculating the performance of the pre-filter A. While the table 106 shows FLOW RATE GPM 1 gpm through 6 gpm, it will be appreciated that other ranges may be included such as through 10 gpm.

Claims

Attorney Docket No: 223644-001301CLAIMSWe claim:

1. A variable flow water treatment system for treating water subject to varying water flow rate demand, the water flow rate demands including a low flow rate and a high flow rate, the system comprising:

a first or pre-filter having an inlet and an outlet, the inlet coupled to a source of water, the pre-filter having a first water treatment contact time sufficient to filter substantially all contaminant from the source of water having a low flow rate, but not sufficient to filter contaminant from the source of water having a high flow rate; and

a second filter having an inlet coupled to the outlet of the pre-filter, the second filter having a second water treatment contact time sufficient to filter substantially all contaminant from the source of water having a high flow rate, the second filter having an outlet from which the filtered water exits.

2. The water treatment system of claim 1 , wherein the pre-filter is a replaceable carbon pre-filter, and wherein the second filter is granular activated carbon filter.

3. The water treatment system of claim 1, further comprising a flow meter for monitoring the rate of flow and a controller unit coupled to the flow meter to indicate anticipated replacement period for the pre-filter. Attorney Docket No: 223644-001301

4. The water treatment system of claim 1, further comprising a flow meter for monitoring the rate of flow and a controller unit coupled to the flow meter to indicate the estimated remaining filter capacity of the pre-filter.

5. The water treatment system of claim 4, wherein the controller unit includes means for estimating the remaining filter capacity of the pre-filter based on the contact time, flow rate and the period of time of the flow rate.

6. The water treatment system of claim 5, further comprising memory having data on the pre-filter regarding estimated filter capacity used by the pre-filter at low flow rates and high flow rates, whereby the data and the monitored flow rate is used by the controller to determine the capacity utilized by the pre-filter in connection with estimating the remaining filter capacity of the pre-filter.

7. The water treatment system of claim 6, wherein the memory includes data on the pre-filter regarding estimated filter capacity used by the pre-filter at flow rates of 1 through 10 gallons per minute.

8. The water treatment system of claim 1, wherein 1 to 3 gpm is considered in a range of low flow rate and 6 gpm or more is considered in a range of high flow rate.

9. The water treatment system of claim 1, wherein the pre-filter' s capacity to filter contaminant from the source of water is selected to incrementally decrease with increasing water flow, whereby the pre-filter' s filtering capacity is over run with higher flow rates. Attorney Docket No: 223644-001301

10. The water treatment system of claim 9, wherein the pre-filter's capacity to filter contaminant from the source of water over a range of water flow rate, is selected to filter more than half of the anticipated demand.

11. The water treatment system of claim 9, wherein the pre-filter's capacity to filter sediment from the source of water over a range of water flow rate, is selected to filter at least 80 percent of the anticipated water demand.

12. The water treatment system of claim 1, further comprising a bypass device having an input and an output, the bypass device is coupled in parallel with the pre-filter, the bypass device is normally closed and has a preset back pressure at which the bypass device opens whenever the back pressure is at or above the preset back pressure.

13. A point-of-entry water treatment system subject to variable water flow rate demand, wherein more than half of the demand is at low flow rates in the range of 2 to 3 gpm, the system comprising:

a first or pre-filter having an inlet and an outlet, the inlet coupled to a source of water, the pre-filter selected based on an ability to filter substantially all of the contaminant from the source of water having a low flow rate including 2 to 3 gpm, and wherein the pre-filter is progressively less effective at filtering the contaminants at increasingly higher flow rates, wherein the pre-filter is ineffective at filtering contaminants at high flow rates, including 8 gpm; and Attorney Docket No: 223644-001301

a second filter having an inlet coupled to the outlet of the pre-filter, the second filter selected based on an ability to filter substantially all contaminant from the source of water having a high flow rate, including a flow rate of 8 gpm, the second filter having an outlet from which the filtered water exits.

14. A process of water treatment in a variable flow rate system, the process comprising:

routing source water through a first or pre-filter having a first water treatment contact time sufficient to filter contaminant from water having a low flow rate, but not sufficient to filter contaminant from influent water having a high flow rate, the pre-filter having an outlet; and

routing the water from the pre-filter through a second filter having a second water treatment contact time sufficient to filter contaminant from water having a high flow rate, the second filter having an outlet from which the filtered effluent water flows out.

15. The process of claim 14, further comprising the steps of monitoring the rate of flow and determining an anticipated replacement period for both the pre-filter and the second filter.

16. The process of claim 15, wherein the steps of monitoring and determining include the steps of determining the rate of flow in gallons per minute, determining the period of time in minutes in which the water flows at the flow rate, using the flow rate (gpm) and time (minutes) of flow rate, calculate the capacity (gallons) utilized by the pre-filter, Attorney Docket No: 223644-001301

wherein the step of calculating includes obtaining and considering the filtering capacity depletion value (gpm) for the determined rate of flow.

17. The process of claim 16, further comprising the step of storing in a memory of the system, filtering capacity depletion values (gpm) for a range of water flow from 1 gpm to 6 gpm.

18. The process of claim 14, further comprising the steps of resetting the programmed pre-filter remaining capacity to 100 percent whenever the pre-filter is replaced in the system.

19. The process of claim 14, further comprising the step of indicating the remaining capacity (percent) of the pre-filter.