Steam Sterilizer Feedwater Control Using Heating Element Temperature Rate
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Solution Overview
Problem
Existing methods for controlling feedwater level in steam sterilizers and generators are costly, prone to errors, and fail to prevent overheating of heating elements, leading to malfunctions and reduced lifespan, while not effectively minimizing energy consumption and non-condensable gases.
Innovation Solution
A method that determines the temperature change rate of the heating element to control feedwater level, allowing demand-based replenishment to prevent overheating, using a heating element with integrated temperature sensors and software for continuous monitoring and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-controlled level regulation with high temperature thresholds (160-210°C) is used to prevent overheating, then heating element protection is improved, but feedwater activation becomes faulty and energy consumption increases
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the temperature change rate (dT/dt) of the heating element and initiating feedwater replenishment before the temperature reaches dangerous thresholds. The control system detects when dT/dt exceeds a predefined rate, indicating insufficient feedwater, and activates replenishment preemptively. This prevents the need to use high temperature thresholds (160-210°C) for protection, thereby avoiding excessive energy consumption while still protecting the heating element.
2Measurement precision
If additional flow sensors or level monitoring components are installed for feedwater detection, then measurement precision is improved, but device complexity and costs increase
Solution Approach 1:
The patent applies self-service by using the heating element's own temperature sensor and control system to monitor feedwater levels indirectly through temperature change rate detection. The existing temperature sensor on the heating element serves dual purposes: controlling heating temperature and detecting feedwater sufficiency. This eliminates the need for additional flow sensors, level monitoring components, or separate measurement systems, thereby maintaining measurement precision while avoiding increased device complexity and costs.
3Device complexity
If fixed temperature switching points with hysteresis are used for level monitoring, then device complexity is reduced, but measurement precision and response accuracy deteriorate
Solution Approach 1:
The patent applies dynamics by replacing fixed temperature switching points with a dynamic monitoring approach based on temperature change rate (dT/dt). Instead of relying on static thresholds with hysteresis, the system continuously calculates the rate of temperature change and compares it against a predefined rate threshold. This dynamic method provides accurate feedwater level detection without requiring complex multi-sensor systems or fixed switching mechanisms, thereby maintaining low device complexity while improving measurement precision.
4Reliability
If temperature thresholds are set high (above sterilization temperature) to ensure reliable operation, then reliability is improved, but feedwater activation occurs too late and energy consumption increases
Solution Approach 1:
The patent applies feedback by continuously monitoring the temperature change rate (dT/dt) of the heating element and using this information to control feedwater replenishment. The system establishes a feedback loop where the temperature sensor detects changes in dT/dt, which serves as an early indicator of insufficient feedwater. When dT/dt exceeds a predefined rate, the system immediately activates feedwater replenishment, providing timely feedback-based control. This maintains operational reliability while enabling early response, avoiding the need to wait for high temperature thresholds to be reached.
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 efficient energy use, reduces overheating, extends heating element lifespan, and improves steam quality by minimizing feedwater quantity and non-condensable gases, while avoiding additional components and costs.
Implementation Method 1
the feedwater is heated by means of a heating element (4), thereby generating steam for the chamber (2)
Implementation Method 2
The steam is generated by evaporating feedwater, particularly demineralized water
Data Source
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AI summary
The invention relates to a method for controlling the feedwater level in a chamber (2) or in a steam generator with an associated chamber (2), in particular a steam sterilizer (1), wherein the feedwater is heated by means of a heating element (4, 4a) and thus steam is generated for the chamber (2). According to the invention, a temperature change rate (ΔT) of the heating element (4, 4a) is determined, and the feedwater is replenished depending on the determined temperature change rate (ΔT) of the heating element (4, 4a). The invention further relates to a corresponding steam sterilizer (1).