Continuous Battery Paste Mixer for Uniform Composition
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Solution Overview
Problem
Conventional batch processes for producing electrochemically active paste for lead-acid batteries result in non-uniform viscosity and composition, difficulty in controlling exothermic heating, clumping of lead oxide, inadequate mixing of fibers and carbon, and challenges in achieving consistent tetrabasic lead sulphate distribution, leading to operational inefficiencies and increased scrap production.
Innovation Solution
A continuous process involving an elongated reactor mixer with a specific ratio of mixing to conveying paddles, sequential injection of water and sulphuric acid, and controlled temperature to produce a uniformly mixed paste with improved fiber and carbon dispersion, allowing for increased fiber and carbon content, and controlled crystal size and morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If batch mixing process is used to produce battery paste, then mixing time is sufficient for chemical reactions, but paste composition and viscosity are non-uniform
Solution Approach 1:
The patent implements a continuous mixing process where lead oxide, water, and sulfuric acid are continuously fed into a mixing reactor to produce battery paste without interruption. This continuous operation eliminates the batch-to-batch variability inherent in traditional batch mixing, ensuring uniform paste composition and viscosity while significantly improving production efficiency.
2Temperature
If conventional batch mixing is used, then equipment complexity is low, but exothermic heating cannot be controlled and localized high temperatures occur
Solution Approach 1:
The patent employs a continuous mixing process with controlled residence time and continuous heat dissipation through the reactor walls. By maintaining steady-state operating conditions and controlling the flow rates of reactants, the exothermic reaction heat is continuously removed, preventing localized high temperatures while maintaining uniform paste temperature throughout the mixing process.
3Stability of the object's composition
If lead oxide is conveyed through pipes and storage, then material handling is efficient, but lead oxide becomes clumped and crusty
Solution Approach 1:
The patent includes a pre-mixing section where lead oxide is initially mixed with a small amount of water to form a slurry before entering the main mixing reactor. This preliminary action prevents lead oxide particles from clumping and caking during conveyance and storage, ensuring uniform particle distribution when the paste is finally produced, thereby eliminating the need for additional breaking or re-mixing steps.
4Strength
If fibers are added to improve paste strength, then mechanical properties improve, but fibers are difficult to disperse and cause clumping
Solution Approach 1:
The patent introduces a dispersant agent that acts as an intermediary between the fiber particles and the paste matrix. This dispersant reduces fiber-fiber interactions and prevents clumping by creating a steric or electrostatic barrier, enabling uniform fiber distribution throughout the paste while maintaining the mechanical strength benefits provided by the fibers.
5Reliability
If carbon is added to improve conductivity, then electrical properties improve, but carbon cannot be incorporated uniformly due to density differences
Solution Approach 1:
The patent employs a high-shear mixing section with intensive turbulent flow that uses hydraulic forces to overcome the density differences between carbon particles and the paste matrix. The intense mixing action suspends carbon particles uniformly throughout the paste, preventing segregation and ensuring consistent electrical conductivity and reliable battery performance.
6Stability of the object's composition
If batch mixing is used, then equipment simplicity is maintained, but tetrabasic lead sulphate distribution is inconsistent
Solution Approach 1:
The patent implements a continuous mixing process with controlled residence time that ensures complete and uniform chemical reactions. The continuous flow through the reactor maintains steady-state conditions, allowing consistent formation and distribution of tetrabasic lead sulphate crystals throughout the paste, eliminating the batch-to-batch variability associated with traditional batch mixing while maintaining high production rates.
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
The continuous process achieves uniform paste composition, enhanced paste strength and conductivity, reduced curing times, and improved battery performance with consistent crystal size and structure, minimizing maintenance and energy costs while maintaining high cycle durability.
Implementation Method 1
a forward screw section formed on each shaft for conveying lead oxide feed material forwardly into the reactor mixer, and a mixing section formed on each shaft extending from the forward screw section to the discharge outlet, each said mixing section comprising a plurality of mixing paddles and conveying paddles in series
Implementation Method 2
exothermic heating resulting from chemical reactions within the paste is difficult to control, producing localized high paste temperatures
Data Source
AI summary
A process and apparatus for continuously mixing and applying paste to battery grids for use in lead-acid battery systems, in which particulate lead oxide, water and sulphuric acid are reacted in an elongated mixer having a mixing to conveying ratio of about 65:35 to 80:20 with controlled reaction temperature for an exit product temperature in the range of above 60° C. to about 80° C. Additives including reinforcing fibers can be added in an amount up to 0.6 wt % of the lead oxide and carbon and graphite powder can be added in an amount up to 6 wt % of the lead oxide.