Solute Concentration Decision for Steam Drum Corrosion Control
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Solution Overview
Problem
In steam turbine plants, the gas-liquid partition coefficient for solutes like ammonia can deviate significantly from literature values, especially at low pressures, leading to improper adjustment of solute concentrations in steam drums, which can result in insufficient corrosion inhibition of equipment.
Innovation Solution
A method to decide the planned solute concentration in feedwater for steam drums based on a target concentration and a capacity coefficient, calculated using actual measurements and considering the mass transfer rate from the liquid to the gas phase, ensuring appropriate solute distribution and corrosion inhibition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gas-liquid partition coefficient from literature is used to decide solute concentration in feedwater, then the calculation is simple, but the solute concentration in the steam drum cannot be properly adjusted, leading to insufficient corrosion inhibition
Solution Approach 1:
The patent changes the parameter from using literature-based gas-liquid partition coefficient to using an empirically determined coefficient that reflects actual plant conditions. This empirical coefficient is derived from measuring the actual solute concentration in the steam drum and back-calculating the effective partition coefficient, thereby adapting the parameter to real-world conditions and resolving the contradiction between calculation simplicity and corrosion protection reliability.
2Device complexity
If the literature gas-liquid partition coefficient is used, then no additional measurements are needed, but the agent concentration in the steam drum deviates from the target range
Solution Approach 1:
The patent implements a feedback mechanism where the actual solute concentration in the steam drum is measured and used to adjust the feedwater solute concentration decisions. The measured concentration from the steam drum is fed back to recalculate the empirical gas-liquid partition coefficient, which then informs subsequent feedwater dosing decisions, creating a closed-loop control system that improves concentration control precision.
3Ease of operation
If feedwater solute concentration is adjusted based on literature values, then the process is straightforward, but corrosion protection is insufficient in low-pressure regions
Solution Approach 1:
The patent applies preliminary action by pre-determining the empirical gas-liquid partition coefficient through initial measurements and calculations before actual operation. This pre-established empirical coefficient accounts for specific plant conditions including low-pressure region characteristics, allowing operators to use straightforward calculations while achieving reliable corrosion protection from the outset.
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 method allows for accurate adjustment of solute concentrations in steam drums, effectively preventing corrosion by maintaining the solute within a target range, even in low-pressure regions, and extends to other steam drums with higher pressures.
Implementation Method 1
a partition ratio of ammonia between the gas and liquid phases (gas-liquid partition coefficient) in the steam drum
Data Source
AI summary
A solute concentration decision method for deciding a planned value CI of a concentration of a solute in a solution to be supplied to a first drum among one or more steam drums for temporarily containing steam generated in a boiler of a steam turbine plant includes a step of deciding the planned value CI of the concentration of the solute in the solution to be supplied to the first drum, on the basis of a target concentration of the solute in the solution in the first drum and a capacity coefficient of the solute in a drum unit including the first drum and an evaporator for generating steam contained in the first drum.