Grease interceptor level analyzer

Abstract

An analyzer for a grease interceptor for measuring levels of fat, oils, and grease (FOG), water, sludge and air having a probe which includes a controller and a sensor sub-unit. Sensor circuits include a microcontroller, timers, and sampling capacitors. The sensor sub-unit includes a plurality of electrode ring pairs coupled to a plurality of timers for converting capacitance measurements to frequencies under the control of a microprocessor in the controller. The frequencies identify the measured levels.

Claims

1. An analyzer for measuring identity of materials and levels of fats, oils, grease, (FOG) water, sludge and air in an interceptor, said analyzer comprising: a probe having an enclosure with a first portion and a second portion, said second portion being secured within said enclosure; said first portion of said probe comprises control means and communication means; said second portion of said probe comprises at least one sensor sub-unit for measuring said levels of FOG, water, sludge and air in said interceptor; said sensor sub-unit comprises a plurality of electrode ring pairs positioned adjacent to each other, and immediately adjacent to an inside surface of said enclosure; a plurality of timers, each of said timers being coupled to each of said electrode ring pairs respectively in said sensor sub-unit for converting a capacitance measurement of each of said electrode ring pairs to a frequency; and a controller, included in said control means of said first portion of said probe, being coupled to each frequency output of each of said plurality of timers for determining said identity of materials and levels of FOG, water, sludge and air in said interceptor.

2. The analyzer as recited in claim 1 wherein a microcontroller in said sensor sub-unit and in response to said controller enables said capacitance measurements to be made in a sequential manner by each of said timers connected to each of said electrode ring pairs.

3. The analyzer as recited in claim 1 wherein each of said electrode ring pairs comprises two adjacent copper strips sandwiched between sheets of plastic and positioned within a sensor sub-unit in a circular formation forming plates of a capacitor, a dielectric of said capacitor being formed by substances within an influence of an electric field generated by said plates.

4. The analyzer as recited in claim 1 wherein said controller comprises means for transmitting said FOG, water, sludge, and air levels and identity of materials to an external receiver.

5. The analyzer as recited in claim 1 wherein said controller comprises a microprocessor having an algorithm for determining said identity of materials including FOG, water, sludge and air at a level of each of said electrode ring pairs.

6. The analyzer as recited in claim 5 wherein said algorithm operating in said microprocessor determines said identity of materials including FOG, water, sludge and air from the value of said frequencies from said timers.

7. The analyzer as recited in claim 5 wherein said algorithm determines the identity of the materials including FOG, water, sludge and air at each of said electrode ring pairs from a function of a range of frequencies converted from outputs of each of said electrode ring pairs.

8. The analyzer as recited in claim 1 wherein said probe comprises a fixed probe when attached to said interceptor, and communicates said FOG, water, sludge and air levels via a low frequency radio signal to a receiver.

9. The analyzer as recited in claim 1 wherein said probe comprises a portable probe for temporary insertion into said interceptor, and said portable probe communicates said FOG, water, sludge and air levels via Bluetooth® Le to an external device.

10. The analyzer as recited in claim 1 wherein said length of said probe is determined by the number of said sub-units daisy chained, one adjacent to another, each of said sub-units comprises a plurality of said electrode ring pairs coupled to a plurality of said timers and including a microcontroller for enabling said capacitance measurement converted to a frequency by each of said timers in a sequential manner.

11. A sensor sub-unit of an analyzer for measuring levels of fats, oils, grease, (FOG) water, sludge and air in an interceptor comprising: a plurality of electrodes positioned adjacent to each other in a circular arrangement; terminals of said electrodes are attached to a printed circuit board (PCB) and positioned within said circular arrangement of said electrodes; a plurality of timers positioned on said PCB, each of said timers receives an input from one pair of said plurality of electrodes forming a plurality of electrode ring pairs; said plurality of timers convert a capacitance measurement at each of said plurality of electrode ring pairs to a frequency, and each end of said sub-unit comprises a means for connecting said sensor sub-unit in a daisy chain arrangement, one sub-unit connected to an adjacent sub-unit, for enabling said capacitor measurement to be made in said interceptor of varying heights.

12. The sensor sub-unit as recited in claim 11 wherein said electrodes comprise metallic electrodes.

13. The sensor sub-unit as recited in claim 11 wherein a microcontroller enables a readout of a capacitance measurement converted to frequency sequentially from an output of each said plurality of timers.

14. The sensor sub-unit as recited in claim 13 wherein a controller receives said capacitance measurement converted to frequency from each of said plurality of timers and determines an identity of materials of said levels of FOG, water, sludge, and air in said interceptor.

15. A method for for measuring identity of materials and levels of fats, oils, grease, (FOG) water, sludge, and air in an interceptor comprising the steps of: providing a probe having a first portion which comprises control means and communication means; providing a second portion of said probe having at least one sensor sub-unit for measuring said levels of FOG, water, sludge, and air in said interceptor; positioning in said sensor sub-unit a plurality of electrode ring pairs adjacent to each other in a circular arrangement and immediately adjacent to an inside surface of said first portion of said probe; converting a capacitance measurement of each of said plurality of electrode ring pairs to a frequency using a plurality of timers, each of said timers being coupled to each of said plurality of electrode ring pairs respectively in said sensor sub-unit; and determining an identity of said materials and said levels of FOG, water, sludge and air in said interceptor using a controller, said controller being included in said control means of said first portion of said probe, and coupled to each frequency output of each of said plurality of timers.

16. The method as recited in claim 15 comprises the step of enabling said capacitance measurement to be made in a sequential manner by each of said timers connected to each of said electrode ring pairs using a microcontroller in said sensor sub-unit and in response to a signal from said controller.

17. The method as recited in claim 15 comprises the step of forming plates of a capacitor wherein each of said electrode ring pairs comprises two adjacent metal strips sandwiched between sheets of plastic and positioned within said sensor sub-unit in said circular arrangement, a dielectric of said capacitor being formed by substances within an influence of an electric field generated by said plates.

18. The method as recited in claim 15 comprises the step of using said controller to determine an identity of materials and levels of said FOG, water, sludge, and air in said interceptor, and transmitting said identity of materials and levels to an external receiver.

19. The method as recited in claim 18 comprises the step of representing by a range of frequencies received from said timer, each of said FOG, water, sludge and air levels, and using an algorithm in a microprocessor of said controller for determining said identity of materials of said FOG, water, sludge and air levels from said range of frequencies.

20. The method as recited in claim 15 wherein said method comprises the step of determining said length of said probe by the number of said sub-units daisy chained, one adjacent to another, each of said sub-units comprises a plurality of said electrode ring pairs coupled to a plurality of said timers and including a microcontroller for enabling said capacitance measurement by each of said timers in a sequential manner.

21. A sensor sub-unit of an analyzer for measuring levels of fats, oils, grease, (FOG) water, sludge and air in an interceptor comprising: a plurality of electrodes positioned adjacent to each other in a circular arrangement; terminals of said electrodes are attached to a printed circuit board (PCB) and positioned within said circular arrangement of said electrodes; a plurality of timers positioned on said PCB, each of said timers receives an input from one pair of said plurality of electrodes forming a plurality of electrode ring pairs; said plurality of timers convert a capacitance measurement at each of said plurality of electrode ring pairs to a frequency; a microcontroller enables a readout of said capacitance measurement converted to frequency sequentially from an output of said plurality of timers; and said sensor sub-unit comprises an enclosure wherein said electrode ring pairs are positioned within said sensor sub-unit immediately adjacent to an inside surface of said enclosure.

22. The sensor sub-unit as recited in claim 21 wherein a controller within said enclosure receives said capacitance measurement converted to a frequency from each of said plurality of timers and determines an identity of materials of said levels of FOG, water, sludge, and air in said interceptor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages, and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which:

(2) FIG. 1 is a graphic illustration of a prior art grease interceptor tank.

(3) FIG. 2 is a graphic illustration of a grease interceptor level analyzer system according to the present invention.

(4) FIG. 3 is a block diagram of capacitance measurement sensor circuits.

(5) FIG. 4 is a schematic diagram of adjacent copper strips embedded in plastic used to form sensor electrodes of a sensor sub-unit.

(6) FIG. 5 is a graphic cutaway illustration of a probe sensor sub-unit with eight pairs of circular sensor electrodes partially opened to show the sensor circuits printed circuit board.

(7) FIG. 6 is a block diagram of a probe controller.

(8) FIG. 7 is a flow chart of the method of FOG probe capacitance measurement sequence of operation according to the present invention.

(9) FIG. 8 is a schematic diagram of the timer circuit in the sensor circuit of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(10) Referring to FIG. 2, a block diagram of a capacitance—based grease interceptor level analyzer (GILA) system 20 is shown for providing in real time fats, oils, grease (FOG), sludge and air level information in an interceptor 10 to a food service establishment (FSE), to an authority having jurisdiction (AHJ) or to an interceptor service company. The GILA system 20 including a probe 22, a probe sensor sub-unit 24, and a controller 26, is contained within an environmentally sealed container 28 such as a plastic pipe. The controller 26 transmits measurement data to a gateway 31 via low frequency radio signal (LoRa) 27. The gateway 31 transmits data to a cloud server and storage 32. Further the controller 26 communicates with a smart device 34 via Bluetooth® LE (BLE) 29, which is a short range wireless technology commonly known in the art.

(11) Still referring to FIG. 2, there are two embodiments of the probe 22, a fixed probe 22 and a portable probe 23. The portable probe 23 communicates via Bluetooth® 29 or short-range wireless technology commonly known in the art to the smart device 34 and displays the levels of FOG, water, sludge and air. It can also send data to the cloud server and storage 32. This embodiment is made principally for municipal inspectors who enforce grease interceptor regulations. For the display and storage of data in a portable probe 23, the user configures the probe 23 through a wireless Bluetooth® Low Energy (BLE) 29 connection. An app for both Android and iOS smart devices provides the user interface for configuring and viewing the probe 23 data.

(12) The fixed probe 22 is permanently enclosed in a grease interceptor 30 (FIG. 2) and communicates, via a low frequency radio signal (LoRa) 27 to a receiver gateway 31 on premises. The receiver gateway 31, in turn, transmits data to a server and cloud-storage service 32. This embodiment is made principally for FSE owners/operators and service companies that pump out the interceptors.

(13) In both embodiments of the probes 22, 23 the enclosure 28 is an environmentally sealed plastic pipe. Inside the probe 22, is a (replaceable) battery, a controller 26, a sensor sub-unit 24 having one or more sensor circuits 40, each mounted on a PC board. The head board with the controller 26 is different for the two versions while the same sensor circuits 40 are used for both.

(14) In FIG. 2, the GILA probe 22 makes periodic capacitance measurements to determine the levels of FOG, water, sludge and air in a grease interceptor 30. The default period time is 15 minutes though the user can change the frequency of readings. The fixed probe 22 is powered by a battery so there is a trade-off between frequency of readings and battery lifetime. At a 15-minute interval between readings, the battery lifetime is approximately one year.

(15) Referring to FIG. 3, a block diagram of sensor circuits 40.sub.1 to 40.sub.8 in the probe 22 is shown. There are eight pairs of electrodes 42 connected to eight timer circuits 46.sub.1 to 46.sub.8 that convert frequency to capacitance, and the eight timer circuits 46 are sequentially activated by a microcontroller 48 enable 50 output. As shown in FIG. 8, a schematic of the timer 46 is provided which measures the capacitance of one of the copper electrode ring pairs 42. There is a timer 46 for each sensor circuit 40.sub.1-40.sub.8 as shown in FIG. 3. The timer 46.sub.1 to 46.sub.8 may be embodied by part no. LMC5551MX/NOPB well known in the art (See FIG. 8). The microcontroller 48 may be embodied by Microchip part no. ATTINY828R-AURCT, commonly known in the art. The LDO 52 is a low drop out voltage regulator, commonly known in the art.

(16) The output of each sensor circuit 40.sub.1 to 40.sub.8 is a square wave clock signal with a frequency that is proportional to the capacitance of each of the electrode ring pairs 42. The timer 46 operates in an astable configuration as shown in FIG. 8. A supply voltage Vcc of 3.3V causes the timer to switch between high and low at a frequency that is proportional to the capacitance: f=1.44/[(R1+R2)×C]. The outputs of all sensor circuits 40.sub.1 to 40.sub.8, each on a small PC board, are wired to a frequency bus 49 that runs along the multiple sensor circuits 40.sub.1-40.sub.8 on the PC board 60 (FIG. 5). Only one of the electrode ring pairs 42 is enabled at a time by the microcontroller 48 to provide a frequency output from each timer 46.

(17) The assembly of eight electrode ring pairs 42, the PC board 60 containing the timers 46.sub.1-46.sub.8, and a microcontroller 48 comprise primarily one sensor sub-unit 24 of the probe 22. Several sensor sub-units 24 can be daisy chained, one adjacent to another, to extend the length of the probe 22 in increments of approximately 8 inches for use in varying heights of interceptors 30. When the sub-unit 24 is the lower unit in a daisy chain configuration as illustrated in FIG. 5, there would be no connections to the terminals 59 in FIG. 5. For example, four sub-units 24 with four PC boards 60 (FIG. 5) containing a total of 32 sensor circuits 40 make a probe 22 that will measure an interceptor 30 approximately 32 inches high.

(18) The microcontroller 48 connected to the sensor circuits 40.sub.1-40.sub.8, outputs each of the sensor frequency values in a sequential manner as directed by the controller 26 (FIG. 6). The controller 26 collects the frequencies generated by their timer circuits 46.sub.1-46.sub.8 and stores the results. The key point is that the microcontroller 48 for the eight sensor circuits 40.sub.1-40.sub.8 controls the readout of the timer 46.sub.1-46.sub.8 operating in an astable mode. In this mode the timer 46 outputs a frequency that is proportional to the capacitance of the electrode ring pairs 42 formed by the eight parallel copper rings 56 (FIG. 4) that senses the interceptor 30 medium.

(19) There are two lines of communication between the sensor circuits 40.sub.1- 40.sub.8 and the controller 26 (see FIG. 6). The Status Line T.sub.x initiates and terminates the capacitance measurement. The two values for the Status Line are LOW and HIGH. The Frequency Line 49 transmits the capacitance measurement to the controller 26 for storage and identity of the various levels within the interceptor 30.

(20) The probe 22 includes a number of sensor-based printed circuit board (PCB) elements. Each sensor circuit 40.sub.1-40.sub.8 PCB comprises the timers 46, and common electronic components, i.e. resistors, capacitors, buffers and LED's). The microcontroller 48 controls all switching and timing functions of the sensor circuits 40.sub.1-40.sub.8.

(21) Referring now to FIG. 4, a schematic of adjacent copper strips that form sensor electrodes 42 as shown for a sensor sub-unit 24 (FIG. 5) of the probe 22. Two adjacent copper strips 52 and 54, are embedded in plastic 55 and constitute one electrode pair 56. Eight pairs of electrodes 56 are provided in one sensor sub-unit 24. The array of 16 copper strips forming electrode ring pairs 42, has typical dimensions of height (H) 4.7 inches, width (W) 0.5 inches of the copper strip, and the array length (L) 8.0 inches.

(22) As described above, there is one dedicated sensor circuit 40 for each capacitance measurement. Each sensor circuit 40.sub.1-40.sub.8 contains a capacitor in the form of two parallel, thin copper electrodes 52 and 54 in a circular formation (FIG. 5). Capacitance values are made relative to water. Eight pairs of electrodes 56, spaced adjacent to each other, form eight electrode ring pairs 42 in one sensor sub-unit 24. The eight pairs of electrodes 56 are spaced at approximately one inch along the length of the probe 22. The entire array of eight pairs of thin copper strip electrodes 56 are sandwiched between two sheets of clear plastic 55.

(23) FIG. 4 shows the array of eight pairs of electrodes 56. Each copper strip 52 has a terminal 57, for connections, to the timer 46 circuit. The timer circuits 46.sub.1-46.sub.8, each sequentially controlled by the microcontroller 48, are mounted on a printed circuit board 60 and connect to the sensor electrode ring pairs 42.

(24) Referring to FIG. 5, a sensor sub-unit 24 of probe 22, comprises printed circuit board (PCB) 60 positioned within the circular sensor electrode ring pairs 42 which are opened up or cut away for illustration purposes in FIG. 5 to show the PCB 60 inside the plurality of rings of electrodes 56. The microcontroller 48 can be seen in the center of the PCB 60. Each of the eight timer circuits 46to 46.sub.8 connect to one pair of electrodes 56 located above the timer circuits. The pair of electrode rings 56 are constructed from thin copper strips 52 sandwiched between sheets of plastic 55 as shown in FIG. 4. When inserted into the enclosure 28 (plastic pipe), the flexible sensor sub-unit 24 conforms to the interior of the enclosure 28. As previously described any number of these sensor sub-units 24 can be connected together to create a probe 22 that is a multiple of eight sensor electrode ring pairs 42. The microprocessor 70 (FIG. 6) in the controller 26 activates the microcontroller 48 of each sub-unit 24 sequentially. Each microcontroller 48 enables each pair of electrodes 56 and measures the electrode pair capacitance via the timer 46, which converts capacitance to a frequency. The result is that the microprocessor 70 in the controller 26 initiates the reading of capacitance of every pair of electrodes 56 from top to bottom in the probe 22 or 23, and determines whether the contents at each pair of electrodes 56 is FOG, water, sludge or air. The proximity of the electrodes 56 against the surface of the probe 22 maximizes the electric field in the interceptor interior and increases the precision of the capacitance measurement.

(25) Referring to FIG. 6, a block diagram of the controller 26 is shown. The controller 26 provides the following three main functions for the probe 22: (1) drives the frequency measurement of each sensor circuit 40.sub.1-40.sub.8. (2) determines the identity of materials and levels of the liquid content of an interceptor 30 such as FOG, water, sludge and air of each sensor circuit 40.sub.1-40.sub.8, and (3) transmits the identity of each level through one of three wireless methods. This controller 26 is attached to a printed circuit board which is referred to as the headboard 50. The controller 26 comprises a microprocessor 70 and communicates with each of the sensor circuits 40.sub.1-40.sub.8 via a serial bus interface 90. The microprocessor 70 is programmed to instruct the microcontroller 48 in each sensor circuit 40 to send an Enable signal 50 to generate the frequency 49 output. The controller 26 communicates the results of the interpreted frequency measurements to the wireless interface 74. The portable probe 23 uses Bluetooth® low energy (BLE) 29 and the fixed probe 22 uses the low radio frequency protocol LoRa 27 or Thread. The wireless interface 74 is also used for control, configuration, and firmware updates.

(26) Still referring to FIG. 6 an external switch 76 turns the controller 26, and therefore the probe 22 or 23, ON and OFF. The temperature sensor 72 provides a temperature reading of the interceptor 30 environment. The LED 78 provides status information to a user. The LED indicator 82 provides a voltage reading of the LiPo battery 84 and the battery charger 80 is controllable by the microprocessor 70 and power management circuit 88, and the power 86 provides voltages to the sensor circuits 40.sub.1-40.sub.8. The microprocessor 70 may be embodied by part number ESP32 by Esprssif, commonly known in the art.

(27) For determining the fluid or material type in an interceptor 30, the capacitance of each sensor circuits 40.sub.1-40.sub.8 or materials as represented by a frequency value is mapped to the identity of the fluid or materials at the sensor electrode ring pairs 42 as being either FOG, water, sludge or air. A lookup table, constructed through laboratory testing, determines the range of frequencies appropriate for each type of fluid or material. For differentiating more accurately between sludge and water or between FOG and air, both pairs of fluids having very similar capacitance values, an algorithm based on the derivative of frequency values is used.

(28) The probe data is embodied in a bar graph such as on a smart device 34 that is divided into horizontal segments. Each segment corresponds to one sensor circuit 40 and is color coded to represent the identity of the material at that level including FOG, water, sludge or air. The total volume of the interceptor 30 contents of FOG and sludge is expressed as a fraction of the interceptor 30 contents. Most Authorities Having Jurisdiction (AHJ) mandate that this fraction be no greater than 25%.

(29) For the display and storage of data in a fixed probe 22, the headboard of the controller 26 of a fixed probe 22 also contains a radio that transmits data either via the LoRa 27 or Thread communication protocol. The radio communicates to a transmitter mounted in the vicinity of the grease interceptor, e.g. on a wall or in an office. The transmitter relays the data to a Cloud-based file 32 via WiFi (802.11 protocol).

(30) Referring to FIG. 7, the steps of the method 100 of capacitance measurements are as follows: Prior to a measurement all sensor circuits 40.sub.1-40.sub.8 are powered OFF and in Step 102 power is turned ON. In Step 104 the microprocessor 70 initializes the system. In Step 106 the selection of a sensor circuit 40.sub.1-40.sub.8 is made. The status line switches to HIGH for 1 millisecond (ms) then LOW for 1 ms and then stays HIGH. In Step 108 oscillations are allowed to stabilize.

(31) In Step 110 the frequency measurement is made as follows: The microcontroller 48 switches the connection to the timer circuit for 4 seconds. This timer 46 outputs a square wave on the frequency line 49. The status line switches to LOW for 1 ms then switches HIGH. This signals that the frequency of the sampling capacitor is to be measured. The microcontroller 48 switches the connection between the sampling capacitor and timer 46 for 4 seconds. This outputs a square wave on the frequency line 49. The frequency of the square wave is proportional to the sample capacitance. The microprocessor 70 adds the values of the frequency to a record.

(32) In Step 112 the sensor circuit 40 address is incremented, and in Step 114 it is determined if there is another sensor circuit, and if so the operation returns to Step 106. Otherwise, the operation goes to Step 116 and the measured data is sent to the server 39, and in Step 118 power is turned OFF. If the operation is returned to Step 106, then a second measurement is made and the values added to the record. The microprocessor 70 continues this loop of Steps 106 to 114 until the microprocessor 70 cannot find the next sensor circuit 40.sub.1-40.sub.8 at which point it completes the record and transmits the data to the controller 26.

(33) The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.