Dynamic Acid Dew Point Control for Corrosion Risk Management
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Solution Overview
Problem
Existing methods for managing corrosion risks in flue gas purification, particularly due to sulfur trioxide, often result in overconsumption of alkaline reagents and fail to account for humidity variations, leading to inefficient energy recovery and increased risk of equipment corrosion.
Innovation Solution
A process that continuously measures and calculates the acid dew point based on humidity and sulfur trioxide content, adjusting the flow rate of neutralization reagents upstream of heat exchangers to maintain a safe temperature margin above the acid dew point, ensuring effective corrosion protection while optimizing energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline reagents are injected upstream at fixed or regulated flow rates to prevent corrosion, then corrosion protection is improved, but reagent consumption increases and energy recovery efficiency decreases
Solution Approach 1:
The patent implements dynamic adjustment of reagent flow rate based on real-time monitoring of acid dew point temperature and flue gas temperature. The control system continuously adapts the injection rate to maintain optimal temperature differential, transitioning from static fixed-rate injection to dynamic responsive injection that matches actual corrosion risk conditions.
Solution Approach 2:
The system employs feedback control by measuring the acid dew point temperature and flue gas temperature, comparing the temperature differential against target ranges, and adjusting the reagent flow rate accordingly. This closed-loop control ensures corrosion protection while optimizing reagent consumption and energy recovery efficiency.
2Reliability
If alkaline reagents are injected in excess to guarantee service temperature above dew point, then corrosion protection is improved, but energy recovery efficiency and reagent utilization decrease
Solution Approach 1:
The patent applies partial action by injecting only the necessary amount of reagent to achieve the target temperature differential (5-30°C), rather than using excessive reagent to guarantee protection. This optimized dosing maintains corrosion protection while improving energy recovery efficiency by avoiding over-neutralization and excessive heat loss.
Solution Approach 2:
The system dynamically changes the reagent injection parameter (flow rate) based on measured temperature conditions and calculated acid dew point. By adjusting this parameter in response to varying flue gas conditions, the system maintains optimal protection margins while maximizing energy recovery efficiency.
3Quantity of substance
If reagent injection is regulated based on acid pollutant content and flue gas flow rate, then acid pollutant management is improved, but humidity variations are not accounted for and corrosion risk remains
Solution Approach 1:
The patent adds a new control dimension by incorporating humidity measurement and acid dew point calculation into the reagent injection control system. This moves beyond the traditional single-dimension control based only on acid pollutant content and flow rate, creating a multi-dimensional control approach that accounts for temperature, humidity, and composition interactions.
Solution Approach 2:
The acid dew point calculation serves as an intermediary parameter that integrates multiple factors (humidity, sulfur trioxide content, temperature) into a single predictive metric. This intermediary enables the control system to account for the combined effects of these parameters on corrosion risk without requiring direct measurement of each individual factor's impact.
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 approach reduces reagent consumption, maintains efficient energy recovery, and effectively prevents corrosion by dynamically adjusting reagent flow rates based on real-time measurements, ensuring the acid dew point remains safely below the treated flue gas temperature.
Implementation Method 1
injection into the fumes to be treated of alkaline reagents, such as lime, magnesia or sodium bisulphite, captures acid pollutants, and in particular sulfur trioxide
Implementation Method 2
the condensation droplets that form are very acidic and can cause significant corrosion in the pipes and for equipment such as filters located downstream
Data Source
Figure 1
Figure 2~3
AI summary
The method involves continuously measuring temperature (TM) and humidity (H) of smoke (1) traversing a bag filter (103). An acid dewpoint value (TDP) is continuously calculated from a measured humidity value and a value of sulphur trioxide content of the smoke. The dewpoint value is continuously compared with the measured temperature value. The quantity of the neutralization reagent (6) introduced into the smoke is increased and decreased, if the difference between the dewpoint and temperature values is lower and higher than two prefix thresholds during two time periods, respectively. The prefix thresholds respectively vary between 5 to 25 degrees Celsius and 10 to 30 degree Celsius. The time periods are between two minutes and one hour. An independent claim is also included for a facility for treating the smoke containing sulphur trioxide and acid pollutants.