Shipboard Ballast Water Treatment Using ORP Feedback Control
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Solution Overview
Problem
Shipboard chlorine-based disinfection systems face challenges in maintaining effective biocide concentrations due to variability in chlorine demand caused by changes in seawater composition, leading to potential corrosion and the formation of disinfection byproducts, especially when dealing with ballast water treatment across different ports with varying nitrogen compound levels.
Innovation Solution
A shipboard water treatment system that utilizes an oxidation reduction potential (ORP) sensor to regulate the introduction of biocides, maintaining a target ORP value between 200 mV to 1000 mV to ensure effective disinfection while minimizing corrosion and byproduct formation, by controlling the rate of biocide introduction based on real-time ORP measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chlorine-based biocides are introduced into ballast water to achieve effective disinfection, then the disinfection effectiveness is improved, but the risk of corrosion and disinfection byproduct formation increases due to variability in chlorine demand
Solution Approach 1:
The patent implements a feedback control system using an ORP sensor to continuously monitor the oxidation-reduction potential of ballast water and automatically adjust the biocide dosing rate. The controller receives ORP sensor signals and modulates the biocide injection to maintain target ORP values (200-1000 mV), creating a closed-loop system that adapts to varying chlorine demand conditions and prevents both under-dosing and over-dosing scenarios that lead to corrosion and byproduct formation
Solution Approach 2:
The patent transitions from traditional fixed-dose or chlorine-concentration-based control to ORP-based control, changing the fundamental parameter used to regulate biocide introduction. By monitoring ORP values (200-1000 mV) instead of fixed chlorine concentrations, the system adapts to varying seawater composition, nitrogen compound levels, and environmental conditions across different ports, maintaining effective disinfection while minimizing harmful effects
2Ease of operation
If fixed-rate biocide introduction is used to simplify system operation, then the ease of operation is improved, but the adaptability to varying seawater conditions deteriorates
Solution Approach 1:
The patent enables the system to self-regulate biocide dosing automatically based on real-time ORP measurements without requiring manual intervention or operator judgment. The ORP sensor continuously monitors water quality, and the controller autonomously adjusts the biocide injection rate to maintain target ORP values, allowing the system to adapt to varying seawater conditions, nitrogen compound levels, and environmental factors across different ports while maintaining simple operation
Solution Approach 2:
The closed-loop feedback control system automatically adjusts biocide dosing based on ORP sensor readings, eliminating the need for manual rate adjustments while adapting to varying chlorine demand. The system receives continuous ORP signals and modulates the biocide injection pump accordingly, providing both operational simplicity and environmental adaptability
3Reliability
If high chlorine concentrations are maintained to ensure disinfection across all conditions, then the disinfection reliability is improved, but the formation of disinfection byproducts and corrosion acceleration worsens
Solution Approach 1:
The patent changes the control parameter from fixed chlorine concentration to dynamic ORP monitoring, allowing the system to maintain effective disinfection (200-1000 mV ORP) while adapting biocide dosing to actual water quality conditions. This prevents excessive chlorine accumulation that leads to byproduct formation and corrosion, while still ensuring reliable disinfection across varying environmental conditions
Solution Approach 2:
The ORP-based feedback control system prevents over-chlorination by continuously monitoring oxidation-reduction potential and automatically reducing biocide dosing when target ORP values are achieved. This feedback mechanism ensures disinfection reliability while minimizing excess chlorine that would otherwise react with organic matter to form disinfection byproducts and accelerate corrosion
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 ensures reliable and effective disinfection of ballast water, reduces the risk of over-chlorination, and minimizes corrosion and byproduct formation, maintaining acceptable biocide levels independent of local seawater conditions, thus protecting ship structures and the environment.
Implementation Method 1
A sensor is provided to measure and transmit a measured signal representative of an oxidation reduction potential of the ballast water
Implementation Method 2
Shipboard electrochlorination systems utilize any of dry chlorine gas, bulk sodium hypochlorite, and in-situ chlorine or sodium hypochlorite electrolytic generators
Implementation Method 3
The electrolysis of seawater to produce chlorine has been used in land-based industrial and offshore applications
Data Source
AI summary
Ballast and/or cooling water biocidal treatment and disinfection systems and techniques are provided. The systems utilize oxidation reduction potential control to regulate addition, or concentration of an electrocatalytically generated biocidal agent to disinfection levels in ship buoyancy and to biofouling levels in ship cooling water systems. The disinfection and biofouling control systems provide suitable treatment while reducing the potential for corrosion of ship components and, in some cases, undesirable disinfection byproducts.