Steam Generator Control Law for Transient Overpressure Mitigation

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Solution Overview

Problem

High-temperature steam electrolysers face challenges in maintaining a homogeneous and regular steam flow, leading to transient overpressures and potential damage due to variations in steam flow rates, which existing solutions like buffer volumes cannot fully address without reducing reactivity and increasing complexity.

Innovation Solution

A device with a helical liquid inlet and a control unit that modulates heating power based on flow rate and temperature, using a non-linear control law to anticipate flow changes and maintain a stable temperature, thereby limiting transient overpressures and optimizing steam generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If buffer volumes are added to limit transient overpressures, then the magnitude of overpressures is reduced, but the responsiveness of the steam generator to setpoint changes is reduced and complexity increases

Engineering Contradiction:

Improvetransient overpressuresVSAvoidevaporator complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The control unit anticipates flow rate changes and adjusts heating power proactively before transient overpressures occur. The non-linear control law modifies heating power based on predicted flow variations, preventing overpressures before they happen rather than reacting after they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors actual flow rate and temperature, comparing them against setpoints and adjusting heating power accordingly. This closed-loop feedback mechanism ensures that transient overpressures are prevented while maintaining responsiveness to setpoint changes.

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If buffer volumes are added to limit transient overpressures, then the magnitude of overpressures is reduced, but the responsiveness of the steam generator to setpoint changes is reduced

Engineering Contradiction:

Improvetransient overpressuresVSAvoidresponsiveness to setpoint changes

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heating power is dynamically adjusted based on real-time flow rate and temperature measurements. The non-linear control law allows the system to adapt its response characteristics, maintaining both pressure stability and responsiveness through continuous dynamic adjustment rather than static buffering.

Inventive Principle:

Principle #15Dynamics

3Productivity

If liquid flow rate is increased to improve steam generation capacity, then steam production increases, but transient overpressures occur due to uncontrolled localized vaporization

Engineering Contradiction:

Improvesteam productionVSAvoidtransient overpressures

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control unit continuously monitors temperature and flow rate, adjusting heating power to match actual liquid flow conditions. This feedback prevents localized vaporization by ensuring heating power is appropriately distributed according to real-time flow variations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The non-linear control law changes heating power parameters based on flow rate and temperature conditions. By dynamically adjusting heating power according to actual operating conditions, the system prevents transient overpressures while maintaining high steam generation capacity.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces transient overpressures, ensures a stable steam flow, and maintains operation at a low average temperature, reducing heat losses and equipment stress, while being simple to implement with a single temperature sensor.

Implementation Method 1

means for heating the evaporation surface

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

converting a liquid into vapor

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3356006B1Device for converting a liquid into vapour and associated method for regulating a heating power

Publication Date: 2021.09.15 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

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AI summary

The invention concerns a device for converting a liquid into vapour comprising: an evaporation surface (17), a liquid inlet (2), heating means (7) for heating the evaporation surface (17), a flow rate regulator (9), a control unit configured to control a flow rate of liquid injected into the liquid inlet (2), an enclosure (6) containing the evaporation surface (17), and a temperature sensor (8) arranged on the evaporation surface (17). The control unit is configured to control a heating power of the heating means (7) depending on a flow rate and a temperature measured by the temperature sensor (8) according to a predefined control law, said predefined control law changing, for each flow rate, in a non-linear manner and inversely proportional to the difference between a reference temperature of the enclosure (6) and the measured temperature.