Stand-alone Pressurization System for Thermowell Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for protecting thermocouples and sensors in harsh environments, such as reactors, are prone to contamination and corrosion due to aggressive gases diffusing through protective layers, leading to frequent failures, and require external gas conduits that introduce unwanted purge gas into the reactor.
Innovation Solution
A stand-alone, closed-circuit modular system comprising a gas container and pressure regulating element connected to the thermowell, maintaining a constant internal pressure higher than the process medium, with a flexible hose for gas expansion and refilling, and a release valve for diverting process medium, creating an inert gas barrier independent of plant utilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a purge gas stream is introduced through a gas conduit inside the thermowell to maintain critical partial pressure of oxygen and sulfur, then the protection of the thermocouple from contamination is improved, but the system complexity increases and unwanted gas is introduced into the reactor
Solution Approach 1:
The invention extracts the gas supply system from the external plant utilities and relocates it into a self-contained cartridge assembly that attaches directly to the thermowell. This removes the need for complex external gas conduits while maintaining the protective atmosphere inside the thermowell.
Solution Approach 2:
The cartridge assembly becomes self-service by incorporating its own gas supply reservoir and pressure regulation mechanisms. The system no longer depends on external plant utilities for gas supply,而是 autonomously maintains the protective atmosphere through integrated components.
2Reliability
If the flow rate of purge gas is increased to maintain critical partial pressure, then the protection effect is improved, but convective cooling of the thermocouple junction increases causing measurement errors
Solution Approach 1:
The pressure regulator in the cartridge assembly provides feedback control by monitoring the pressure inside the thermowell and automatically adjusting the gas flow rate. This ensures the minimum pressure needed for protection is maintained without excessive flow that would cause convective cooling and measurement errors.
Solution Approach 2:
The system changes the parameter control approach from flow-rate-based to pressure-based control. By regulating pressure rather than flow rate, the system achieves protection while minimizing convective cooling effects that would otherwise cause temperature measurement inaccuracies.
3Reliability
If a stand-alone closed-circuit system is used to maintain constant internal pressure, then the protection reliability is improved and external gas supply is eliminated, but the device complexity increases
Solution Approach 1:
The system is segmented into a modular cartridge assembly that attaches to the thermowell, separating the gas supply function from the temperature measurement function. This segmentation allows the complex pressurization system to be isolated in a removable cartridge, simplifying installation and maintenance while providing reliable protection.
Solution Approach 2:
The cartridge assembly contains nested components including the gas reservoir, pressure regulator, and connection mechanisms within a compact housing. This nesting approach consolidates multiple functions into a single integrated unit that attaches to the thermowell, reducing overall system complexity despite the advanced 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
The system effectively protects sensors by maintaining a controlled internal pressure, preventing contamination and extending the working life of measuring probes by creating a counter-pressure barrier against aggressive gases, reducing corrosion and drift, and operating autonomously without relying on external gas supplies.
Implementation Method 1
a pressure regulating element, wherein the pressure regulating element is connectable to the thermowell and to the container in a gas tight and pressure tight manner and wherein the pressure regulating element serves for regulating the pressure in the thermowell to a predetermined pressure value
Implementation Method 2
aggressive process gases like chlorides, sulphides, hydrocarbons, but also oxygen and hydrogen, can cross the different protective layers and enter into the sensitive part of the probe. This may be due, for example, to the fact that ceramics can become porous at high temperature. This diffusion and/or permeation phenomenon can cause corrosion
Implementation Method 3
a flexible hose, via which hose the pressure regulating element is connectable to the thermowell and which is designed to be a volume reservoir for gas expanding due to an increasing temperature of the gas inside the thermowell
Data Source
Figure 1~2
Figure 3
AI summary
A stand-alone modular system (20) for pressure compensation of a thermowell (9), comprising: a gas container (7), which gas container (7) is filled with a limited amount of a, preferably inert, gas and which container serves as a pressure reservoir for the thermowell (9), a pressure regulating element (2), wherein the pressure regulating element (2) is connectable to the thermowell (9) and to the container (7) in a gas tight and pressure tight manner and wherein the pressure regulating element (2) serves for regulating the pressure in the thermowell (9) to a predetermined pressure value.