Process Probe Heater Shutoff for Flameout Protection

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Solution Overview

Problem

Existing combustion process analyzers face risks of explosion due to high-temperature sensors in the combustion zone and require additional hardware like flame arrestors or scanners, which increase complexity and cost, while existing methods to address flameout conditions may inhibit measurement access and accuracy.

Innovation Solution

A process combustion transmitter with a probe having a measurement cell heated above the fuel's flashpoint, featuring electronic circuitry that automatically disengages the heater once sufficient process heat is maintained, eliminating the need for a flame scanner and potentially reducing the necessity for a flame arrestor by ensuring the measurement cell cools passively during a flameout.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flame arrestor is added over the diffuser to quench explosions, then safety is improved, but measurement lag increases and system complexity increases

Engineering Contradiction:
Improveflameout protectionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the flame arrestor component from the system entirely. Instead of adding protective hardware, the solution extracts the hazard by cooling the measurement cell below the flashpoint when flameout is detected, eliminating the need for flame arrestors and their associated complexity and measurement lag.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a gaseous buffer (nitrogen or other inert gas) as an intermediary substance. When flameout is detected, this gas is directed to the measurement cell to displace unburned fuel and create a protective atmosphere, serving as a mediator between the hazardous combustion environment and the sensitive measurement cell.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the measurement cell is heated above flashpoint for measurement, then measurement capability is improved, but explosion risk increases during flameout

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidignition risk
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic temperature control of the measurement cell. The cell is heated above flashpoint during normal operation for measurement capability, but automatically cooled below flashpoint when flameout is detected. This dynamic adjustment of operating conditions allows the system to maintain measurement capability while eliminating ignition risk during hazardous conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies preliminary anti-action by detecting flameout conditions and immediately cooling the measurement cell below the flashpoint before any potential ignition can occur. This preemptive cooling action prevents the harmful effect of ignition before it can happen, rather than relying on post-ignition mitigation.

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If a gaseous buffer is created to protect the measurement cell, then safety is improved, but additional hardware and system cost increase

Engineering Contradiction:
Improveflameout protectionVSAvoidhardware complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the existing nitrogen supply system multi-functional. The nitrogen line serves both its original purpose and the additional function of creating a protective gaseous buffer in the measurement cell during flameout. This eliminates the need for separate protective hardware while providing comprehensive safety.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This solution provides enhanced flameout protection without additional hardware, reducing system complexity and cost, while maintaining measurement accuracy and accessibility, and allows for broader application in hazardous environments.

Implementation Method 1

The process probe includes a heater configured to heat the measurement cell to the operating temperature

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a temperature sensor, and to the heater. The electronic circuitry is configured to disengage power to the heater once process combustion heat is sufficient to maintain the measurement cell at the operating temperature as indicated by the temperature sensor indicating the probe has reached a heater shutoff threshold

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 3

once process combustion heat is sufficient to maintain the measurement cell at the operating temperature

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2979031B1In situ heated process probe
Publication Date: 2020.02.26 ROSEMOUNT INC
  • EP2979031B1 patent drawingFigure 1
  • EP2979031B1 patent drawingFigure 2
  • EP2979031B1 patent drawingFigure 3

AI summary

A process combustion transmitter (10) is provided. The transmitter (10) includes a process probe (12) extendible into a flow of process combustion exhaust. The process probe (12) has a measurement cell (36) with an operating temperature that is above a flashpoint of process combustion fuel. The process probe (12) includes a heater (38) configured to heat the measurement cell (36) to the operating temperature. Electronic circuitry is coupled to the measurement cell (36) and to the heater (38). The electronic circuitry is configured to disengage power to the heater (38) once process combustion heat is sufficient to maintain the measurement cell (36) at the operating temperature and thereafter to maintain the heater (38) in a de-energized state.