Volatile Fatty Acid Control in Papermaking via Conductivity Feedback
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Solution Overview
Problem
Papermaking systems face challenges in controlling volatile fatty acids (VFAs) due to high concentrations of facultative anaerobes, which produce odorous and hazardous organic gases, and existing methods rely on aeration to increase dissolved oxygen, which is inefficient.
Innovation Solution
A method involving the use of sensors to measure dissolved oxygen and conductivity levels in process water, with the addition of a control agent such as biocide, sodium bisulfite, or carbamate to reduce VFA concentrations by adjusting the oxygen levels and inhibiting bacterial production of VFAs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aeration is used to increase dissolved oxygen content in process water, then VFA levels are reduced, but energy consumption increases and the process becomes less efficient
Solution Approach 1:
The patent changes the parameter being monitored from dissolved oxygen level to conductivity level. By measuring conductivity, which correlates with VFA concentration, the system can trigger aeration only when VFAs are actually high, rather than continuously maintaining high dissolved oxygen levels. This reduces unnecessary aeration energy consumption while still achieving VFA control.
Solution Approach 2:
The patent implements a feedback control system where conductivity is continuously measured and used to adjust aeration timing. The controller compares conductivity readings against setpoints and activates aeration only when VFA levels exceed thresholds, creating a responsive feedback loop that minimizes energy use while maintaining VFA control.
2Quantity of substance
If dissolved oxygen is continuously maintained at high levels through aeration, then VFA production is suppressed, but oxygen consumption increases and process efficiency decreases
Solution Approach 1:
The patent replaces continuous aeration with periodic, on-demand aeration triggered by conductivity measurements. Instead of continuously supplying oxygen to suppress VFA production, the system performs intermittent aeration only when conductivity indicates high VFA levels, significantly reducing oxygen consumption and energy loss.
Solution Approach 2:
The system performs preliminary measurement of conductivity to determine when aeration is needed, rather than continuously aerating. This preliminary detection allows the system to activate aeration only when necessary, preventing unnecessary oxygen consumption and energy waste.
3Use of energy by moving object
If conductivity monitoring is used to trigger control agent addition, then VFA control is achieved without continuous aeration, but system complexity increases due to additional sensors and control logic
Solution Approach 1:
The patent uses conductivity as an intermediary parameter to indirectly measure VFA concentration. Instead of directly measuring VFAs or continuously monitoring dissolved oxygen, the system uses conductivity—a readily measurable parameter that correlates with VFA levels—as a mediator to trigger control actions, simplifying the overall measurement and control system.
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
Effectively reduces VFA concentrations by up to 100% in papermaking systems, preventing odor and gas production, and can be implemented in closed water loops without the need for aeration.
Implementation Method 1
measuring the dissolved oxygen in the process water to obtain an input signal
Implementation Method 2
adding an effective amount of a control agent to the process water... the control agent inhibits the formation of the volatile fatty acid
Data Source
AI summary
A method of controlling a volatile fatty acid in an aqueous industrial system is provided in the present disclosure. The method includes determining a level of dissolved oxygen in process water in the aqueous industrial system and adding an effective amount of a control agent to the process water if the determined level of dissolved oxygen is above a predetermined level. The compositions and methods can lower the amount of VFA present in the aqueous industrial system.