Urea Decomposition Control Using Residual Bromine-Chlorine Separation
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Solution Overview
Problem
Existing methods for urea decomposition in ultrapure water production inaccurately measure free chlorine concentration due to the inclusion of free bromine, leading to improper addition of chlorine oxidizers, which affects the efficiency and duration of the urea decomposition process.
Innovation Solution
A method and device that measure and control the concentrations of residual free bromine and chlorine in treated water to optimize the addition of bromide salt and chlorine-based oxidizers, using a residual chlorine meter with a compound to differentiate between free bromine and chlorine, and adjust the amounts based on calculated reaction rate constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a residual chlorine meter is used to measure free chlorine concentration in treated water containing both free chlorine and free bromine, then the measurement process is simple, but the measured value includes both free chlorine and free bromine concentrations, leading to inaccurate free chlorine concentration data
Solution Approach 1:
The patent divides the measurement of residual chlorine into two separate measurements: first measuring the total residual chlorine (free chlorine + free bromine), then measuring only free bromine concentration. By subtracting the free bromine concentration from the total residual chlorine, the accurate free chlorine concentration is obtained. This segmentation resolves the contradiction by maintaining operational simplicity while achieving measurement precision.
Solution Approach 2:
The patent introduces free bromine concentration as an intermediary measurement. By measuring free bromine separately and using it as a subtractive component from the total residual chlorine, the system isolates the free chlorine concentration accurately. This intermediary approach allows the residual chlorine meter to function simply while achieving precise free chlorine measurement.
2Ease of operation
If the amount of chlorine-based oxidizer is determined based on inaccurate residual chlorine meter readings that include free bromine, then the control process is straightforward, but the appropriate amount of oxidizer is not added, affecting urea decomposition efficiency
Solution Approach 1:
The control system segments the oxidizer dosage calculation into two parts: determining the amount needed for free bromine neutralization and the amount needed for urea decomposition based on accurate free chlorine concentration. This segmentation ensures that the control process remains straightforward while achieving optimal urea decomposition efficiency by using precise concentration data.
Solution Approach 2:
The patent implements a feedback control system where the measured free chlorine concentration (after subtracting free bromine) is used to adjust and optimize the chlorine-based oxidizer dosage. This feedback mechanism ensures that the appropriate amount of oxidizer is added for urea decomposition, resolving the contradiction between operational simplicity and decomposition efficiency.
3Device complexity
If free bromine concentration is not separately measured and subtracted from total residual chlorine, then the measurement and control process remains simple, but the amount of bromide salt and chlorine-based oxidizer cannot be optimized
Solution Approach 1:
The system segments the chemical additive optimization into two independent calculations: one for bromide salt based on free bromine concentration and another for chlorine-based oxidizer based on free chlorine concentration. This segmentation allows precise optimization of chemical quantities while keeping the overall system complexity manageable through sequential processing.
Solution Approach 2:
The patent uses free bromine concentration as an intermediary value that enables optimization of both bromide salt and chlorine-based oxidizer dosages. By measuring and subtracting free bromine, the system obtains accurate free chlorine data, which together allow precise optimization of chemical additive amounts without excessive 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
Optimizes the amount of chlorine oxidizers for efficient urea decomposition, ensuring accurate and timely completion of the process.
Implementation Method 1
a bromide salt and a chlorine-based oxidant are added to pre-treated water containing urea to generate hypobromite ions to decompose urea
Data Source
AI summary
A urea treatment method in which hypobromite ions are generated by adding a chlorine-based oxidizer and a bromide salt to to-be-treated water containing urea so as to break down the urea in the to-be-treated water and obtain treated water, the method including: a) determining the free residual bromine concentration and the free residual chlorine concentration in the treated water; and b) controlling the added amount of the chlorine-based oxidizer and the bromide salt on the basis of the free residual bromine concentration and the free residual chlorine concentration. The device includes a bromide salt adding means, a chlorine-based oxidizer adding means, a urea decomposition tank, a residual chlorine meter, and a control device for controlling the added amount of the chlorine-based oxidizer by the chlorine-based oxidizer adding means on the basis of the method.