Thermal Camera Flame Detection Spectral Ratio Analysis

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Solution Overview

Problem

Current flame detectors in industrial environments face challenges with false alarms due to radiation sources other than flames, such as heaters, sunlight, and reflections, and are affected by temperature, smoke, and oil vapors, leading to inefficient fire detection.

Innovation Solution

A flame detection system utilizing a combination of thermal cameras and infrared sensors to generate thermal image data and infrared sensor data, processing these to create spectral features and feature maps, which help differentiate between actual flames and false alarms, and transmit accurate alarm signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical cameras including infrared or ultraviolet cameras are used for flame detection, then flame detection capability is provided, but false alarms occur from radiation sources that are not flames such as heaters, welders, the sun, and reflections

Engineering Contradiction:
Improveflame detection accuracyVSAvoidradiation source discrimination
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The system segments the detection task by dividing it into multiple spectral bands (e.g., 3.7-4.8 microns for CO2 detection, 2.0-2.5 microns for H2O detection) and uses multiple sensors to detect different spectral characteristics. This segmentation allows the system to analyze the spectral fingerprint of radiation sources and distinguish flames from other sources based on their unique spectral signatures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the detection parameter from simple intensity detection to multi-spectral analysis. By measuring radiation intensity across multiple wavelength bands and analyzing spectral ratios (e.g., CO2 band ratio, H2O band ratio), the system transforms the detection approach to identify flames based on their characteristic spectral parameters rather than just overall radiation intensity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If infrared detectors are used, then flame detection is enabled, but the detectors are affected by temperature and subject to false alarms from IR sources

Engineering Contradiction:
Improveflame detection capabilityVSAvoidtemperature interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system compensates for temperature interference by using spectral ratio analysis. Instead of relying on absolute intensity measurements that are temperature-dependent, the system calculates ratios of intensities at different wavelengths (e.g., I4.3/I3.7 for CO2, I2.7/I2.0 for H2O). These ratios remain relatively stable across different temperatures and provide characteristic fingerprints for flame detection, effectively eliminating temperature-related false alarms.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If ultraviolet detectors are used, then flame detection is enabled, but the detectors are affected by smoke and oil vapors on optics

Engineering Contradiction:
Improveflame detection capabilityVSAvoidoptics contamination
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system transitions from ultraviolet detection to infrared spectral detection, moving to a different dimensional approach in the electromagnetic spectrum. By detecting flame radiation in the infrared region (3.7-4.8 microns for CO2, 2.0-2.5 microns for H2O) rather than ultraviolet, the system avoids the problem of smoke and oil vapor interference that plagues UV detectors, while still achieving reliable flame detection through spectral fingerprint analysis.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 system effectively reduces false alarms by using spectral features and feature maps to distinguish between flame and non-flame radiation sources, enhancing the accuracy of fire detection and reducing unnecessary alerts.

Implementation Method 1

a thermal camera configured to generate thermal image data

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

an infrared sensor configured to generate infrared sensor data

Methodology Applied
Scientific EffectInfrared radiation detection: Infrared Radiation

Data Source

PatentUS11990017B2Thermal camera and infrared sensor based flame detection
Publication Date: 2024.05.21 HONEYWELL INTERNATIONAL INC
  • US11990017B2 patent drawing
  • US11990017B2 patent drawing
  • US11990017B2 patent drawing

AI summary

Apparatuses, systems, methods, and computer program products for flame detection are provided. An example of a flame detection apparatus includes an infrared sensor to generate infrared sensor data and a thermal camera to capture one or more thermal images and generate thermal image data. The flame detection includes detecting if a flame is present in an environment based on the infrared sensor data and the thermal image data, including determining if one or more false alarms are present. The flame detection may also be based one or more spectral features or thermal features.