Steam Generator Overheating Detection via Temperature Difference
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Solution Overview
Problem
Existing steam generator systems face challenges in reliably detecting water shortages, leading to potential overheating and damage due to limitations in drum water level measurement and temperature gradient monitoring, particularly in systems with storage furnaces where water supply can fail, causing irreversible material changes and stress corrosion cracking.
Innovation Solution
A method and device that measure the temperature difference between the steam drum and the steam discharge pipe, using continuous pressure and temperature measurements to detect incipient overheating, allowing for early intervention to prevent damage by signaling operators to halt further heat supply and assess operational data for potential hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If drum water level measurement is used for water shortage protection, then water level control is achieved, but reliable detection of water shortages below measurable minimum is not possible
Solution Approach 1:
The patent introduces an intermediary measurement approach by measuring the temperature of the water-steam mixture in the steam discharge pipe as an indirect indicator of evaporator cooling status. This intermediary measurement allows detection of water shortages even when the drum water level falls below the measurable minimum range, thereby resolving the contradiction between measurement range and detection reliability.
Solution Approach 2:
Instead of directly measuring drum water level to detect water shortages, the patent inverts the approach by measuring the temperature of the water-steam mixture in the steam discharge pipe. This inverted measurement approach provides reliable detection of water shortages regardless of drum water level, resolving the limitation of direct water level measurement.
2Reliability
If automatic firing shutdown is triggered by water level deviation, then evaporator overheating is prevented, but time-consuming destructive or non-destructive tests are required to assess damage
Solution Approach 1:
The patent performs preliminary assessment of evaporator damage by continuously monitoring the temperature difference between the water-steam mixture and boiling temperature. This preliminary monitoring provides information about the thermal state of the evaporator before shutdown, allowing operators to assess whether component damage has occurred without requiring time-consuming destructive or non-destructive tests after the incident.
Solution Approach 2:
The patent implements feedback by continuously monitoring the temperature difference and using this information to assess evaporator condition. The feedback mechanism provides real-time information about evaporator cooling status, enabling operators to make informed decisions about potential damage without requiring extensive post-incident testing.
3Reliability
If temperature difference monitoring is implemented, then incipient overheating is detected early, but additional temperature measurement devices and complexity are required
Solution Approach 1:
The patent makes the temperature measurement in the steam discharge pipe serve multiple functions: it monitors both the water level status in the drum and the cooling status of the evaporator. This multi-functionality allows early detection of incipient overheating without requiring separate dedicated measurement devices, thereby resolving the contradiction between detection reliability and system complexity.
Solution Approach 2:
The patent merges the water level monitoring function and evaporator cooling status monitoring function into a single temperature measurement system. By combining these functions, the patent achieves reliable overheating detection while minimizing the number of additional measurement devices required, thus reducing system complexity.
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
Enables independent assessment of natural circulation function and component safety without complex tests, preventing damage from overheating and sudden cooling of evaporator tubes by providing timely alerts and measures to maintain safe operating conditions.
Implementation Method 1
The invention relates to steam generators that are operated in temperature equilibrium between drum steam, drum water and downpipe water
Implementation Method 2
The cause of this 'non-destruction' lies in the sometimes large difference between the density of the boiling water in the downpipe and the density of the water-steam mixture in the evaporator tube (riser tube)
Implementation Method 3
a measuring device (9) for the medium temperature is arranged in the steam discharge pipe (8) between the evaporator (7) and the steam drum (4)
Implementation Method 4
The boiling temperature in the steam generator is calculated from the pressure measured in the steam generator, preferably in the steam drum
Data Source
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AI summary
The method involves measuring media temperature of a water vapor mixture comes from vaporizer (7) in a vapor exhausting pipe (8) by a measuring device (9) at a point before the entering a vapor drum (4) using a sensors in a thermometer pocket. A boiling temperature (13) in the drum is measured or computed, and a temperature difference (14) is determined from the boiling temperature in the drum measured by the measuring device and the media temperature in the pipe. A value is provided to release a signal (16), with which the pocket is introduced by switching off of a system. An independent claim is also included for a device for performing a method for operating a steam generator.