Rotating Drum Vacuum Deaerator for Coating Gas Removal
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Solution Overview
Problem
Existing vacuum deaerators are inefficient in removing gas from high-viscosity coating materials, leading to uneven coating surfaces and uncoated spots, as they either fail to break small air bubbles under high vacuum or cause solvent evaporation and quality deterioration when increasing vacuum or device size.
Innovation Solution
A method and apparatus with a rotating drum inside a vacuum tank, maintaining an absolute pressure of 3-15 kPa, using stepped drum surfaces and vanes to control film thickness and bubble breaking, ensuring efficient gas removal without solvent evaporation, and allowing for monitoring and control of operational parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum level is increased to improve gas removal efficiency, then gas exhaustion improves, but solvent evaporation increases causing quality deterioration
Solution Approach 1:
The deaeration process is divided into multiple stages with different vacuum levels. A roughing stage removes large gas bubbles at higher vacuum levels, followed by a finishing stage that removes remaining small bubbles at lower vacuum levels. This segmentation allows efficient gas removal while preventing excessive solvent evaporation that would occur with continuously high vacuum.
Solution Approach 2:
The vacuum process is applied periodically in controlled cycles rather than continuously at maximum vacuum. The system alternates between vacuum application and pressure equalization phases, allowing gas to be removed in controlled bursts while giving the solvent time to re-equilibrate and reducing overall evaporation losses.
2Productivity
If device size is increased to improve separating capacity, then gas removal capacity increases, but manufacturing costs increase markedly
Solution Approach 1:
Instead of one large expensive deaerator, the system uses multiple smaller deaeration chambers or stages working in sequence. Each chamber handles a portion of the total gas removal task, allowing the use of smaller, more cost-effective components while achieving the same overall separating capacity through cumulative effect.
Solution Approach 2:
The deaeration system employs a nested configuration where smaller deaeration chambers are arranged within or alongside larger structural components. This nesting allows efficient use of space and enables the system to achieve high separating capacity without requiring a single large-scale expensive device.
3Productivity
If mixing period is extended to improve gas removal, then gas exhaustion improves, but functional capacity of deaerators remains too low requiring more devices
Solution Approach 1:
The system incorporates mechanical vibration or agitation during the deaeration process to accelerate gas bubble formation and detachment. This vibrational action disrupts the coating material temporarily to release trapped gases much faster than passive mixing, achieving effective gas removal in significantly reduced time without requiring extended mixing periods.
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
Rapid and effective gas exhaustion from coating materials, preventing quality deterioration and enhancing coating uniformity by maintaining a stable pressure and controlling bubble formation, thus improving deaeration efficiency and capacity.
Implementation Method 1
the rotating motion of the drum causes the coating material to rise up the inner wall of the drum and to discharge from the upper edge of the drum as a thin film against the inner wall of a vacuum tank
Implementation Method 2
means for providing a vacuum in the tank
Implementation Method 3
maintaining an absolute pressure of 3-15 kPa
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method and apparatus for exhausting gas from a coating material. The coating material is fed in the bottom part area of a drum (3) rotating around an essentially vertical axis inside a vacuum tank (1), whereby the rotating motion of the drum causes the coating material to rise up the inner wall of the drum and to discharge from the upper edge of the drum as a thin film against the inner wall of a vacuum tank, wherefrom the coating material flows downwards. In the method, the coating material is arranged to rise up the wall of the drum stepwise, so that the coating material will form a thin veil-like film on at least two different step levels (10- 12), whereupon the gas bubbles in the coating material will break and be discharged from the coating material.