F.O.G. Detection Sensor Using Thermal Conductivity Discrimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing grease and oil removal systems face inefficiencies due to reliance on timers for skimming operations, leading to wasted energy and potential for foul odors and electronics damage from decomposing food solids, and existing sensors like thermocouples are costly and vulnerable to corrosive effluent conditions.
Innovation Solution
A sensor apparatus using a thermally conductive substrate with a resistor and thermistor, encapsulated in an electrical insulator, which applies heat and measures temperature rise ratios to differentiate between F.O.G. and water, allowing for efficient and energy-conscious operation of grease separators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a timer-based skimming operation is used, then the skimming apparatus operates automatically, but energy is wasted when F.O.G. is not present and the separator runs unnecessarily
Solution Approach 1:
The patent employs a sensor that detects the presence or absence of F.O.G. in the effluent and provides feedback to the control system. This feedback mechanism allows the skimming apparatus to operate only when F.O.G. is detected, eliminating energy waste from unnecessary operations while maintaining automatic control. The sensor monitoring and conditional activation create a closed-loop system that adapts to actual F.O.G. presence.
Solution Approach 2:
The system uses a sensor that automatically detects F.O.G. presence and triggers skimming operations without human intervention. The sensor-based detection and automatic activation enable the system to serve itself by determining when skimming is needed, eliminating the need for manual scheduling while preventing energy waste through intelligent operation timing.
2Productivity
If the skimmer operates continuously to remove all F.O.G., then F.O.G. removal efficiency is maximized, but the exposed water allows food solids to decompose and generate foul odors
Solution Approach 1:
The patent implements partial skimming action by operating the skimmer only when F.O.G. is detected above certain thresholds, rather than continuously removing all F.O.G. The sensor-based control allows the system to perform sufficient F.O.G. removal to meet operational requirements while avoiding excessive skimming that would expose food solids to decomposition. This selective operation maintains productivity while preventing odor generation.
Solution Approach 2:
The system changes the operational parameter from continuous skimming to intermittent skimming based on F.O.G. detection. By monitoring F.O.G. presence and adjusting skimmer operation accordingly, the system achieves adequate F.O.G. removal without the harmful effect of exposing food solids. The parameter change from constant to conditional operation resolves the contradiction between removal efficiency and odor prevention.
3Measurement precision
If thermocouples are used for F.O.G. detection, then temperature-based discrimination is achieved, but the sensor is vulnerable to corrosive effluent and has high cost
Solution Approach 1:
The patent replaces expensive thermocouples with a more economical sensor system that uses temperature-sensitive materials or electronic components less susceptible to corrosion. The new sensor provides adequate measurement precision for F.O.G. detection while being more reliable in corrosive effluent environments. This substitution aligns with using cost-effective, durable components suitable for the harsh operating conditions.
Solution Approach 2:
The system changes the detection parameter or method from thermocouple-based temperature measurement to an alternative sensing mechanism that is less vulnerable to corrosion. This parameter change maintains the ability to discriminate between F.O.G. and water while improving sensor reliability in corrosive environments. The alternative detection approach avoids the weaknesses of thermocouples in this application.
4Device complexity
If a timer-based system is used, then operation scheduling is simple, but the system cannot adapt to variations in operation schedules such as weekdays vs. weekends or seasonal changes
Solution Approach 1:
The patent implements a sensor-based system that automatically detects F.O.G. presence and determines when skimming is needed, eliminating the need for complex scheduling programs. The sensor monitors effluent conditions in real-time and triggers operations based on actual F.O.G. presence rather than predetermined schedules. This self-service approach adapts automatically to any operational pattern, whether weekday/weekend variations, seasonal changes, or irregular schedules, while keeping the control system relatively simple.
Solution Approach 2:
The system transitions from a static timer-based schedule to a dynamic sensor-responsive operation mode. The skimmer operation becomes adaptable to changing conditions by responding to real-time F.O.G. detection rather than following a fixed schedule. This dynamic approach allows the system to automatically adjust to any operational pattern without requiring complex programming, achieving both adaptability and simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively discriminates between F.O.G. and water, reducing energy waste and preventing odor-related issues, while being cost-effective and resilient to corrosive environments, thereby enhancing the efficiency and longevity of grease removal systems.
Implementation Method 1
A sensor unit includes a heater that applies heat to a sensor portion of the sensor unit
Implementation Method 2
A thermistor is also mounted to the substrate with two leads to enable a current to be passed through the thermistor to generate a datum indicative of thermistor temperature
Implementation Method 3
Water and F.O.G. both dissipate (conduct) heat, but at different rates. By heating up a sensor unit and measuring how fast it gets hot one can measure how easily the heat is dissipated in the surrounding media
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
An apparatus for discriminating between liquids having differing thermal conductivities includes a thermally conductive substrate, a resistor and a thermistor mounted to the thermally conductive substrate. Two leads on the resistor enable a current to be passed through the resistor to generate heat, and two leads on the thermistor enable a current to be passed through the thermistor to generate a datum indicative of thermistor temperature. An electrical insulator encapsulates the resistor, the thermistor and part of the thermally conductive substrate. A remainder of the thermally conductive substrate may extend beyond the electrical insulator to provide a thermal path from the resistor and thermistor to a liquid in which the apparatus may be immersed.