Multi-Pipe Distribution for Down Flow Vessel Liquor
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Solution Overview
Problem
In high-capacity chemical pulp manufacturing processes, existing systems for adding treatment liquors to comminuted cellulose materials in down flow vessels face issues with uneven distribution, leading to chemical concentration gradients, chip plug blockages, and steam channeling, which result in inconsistent pulp quality and increased rejects.
Innovation Solution
The solution involves a distribution system using multiple vertical pipes connected to a common header, positioned radially within the vessel to ensure even alkali distribution and minimize interference with the plug flow, reducing steam velocity and the risk of channeling by flashing steam within the chip pile, thereby maintaining uniform treatment across the vessel's cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single central pipe or annular distribution nozzles are used to add treatment liquor in large diameter vessels, then the system is simpler to operate, but the treatment liquor is not evenly distributed over the entire cross-sectional area resulting in chemical concentration gradients
Solution Approach 1:
The treatment liquor addition system is segmented into multiple separate pipes or nozzles distributed across the vessel cross-section, replacing a single central pipe or annular nozzle. This segmentation allows treatment liquor to be delivered to multiple locations simultaneously, ensuring even distribution across the entire chip cross-sectional area and eliminating chemical concentration gradients while maintaining operational simplicity through standardized pipe configurations.
2Manufacturing precision
If multiple pipes are used to improve distribution, then uniformity of treatment is improved, but device complexity increases
Solution Approach 1:
The distribution problem is extracted from the vessel wall and solved by positioning multiple pipes inside the vessel, taking out the complexity from the wall structure and placing it within the vessel where it can be more effectively managed. This allows each pipe to be independently positioned and controlled, achieving uniform treatment without requiring complex wall-integrated distribution manifolds.
Solution Approach 2:
Different regions of the vessel cross-section are served by dedicated pipes positioned at appropriate locations, allowing each region to receive treatment liquor with locally optimized flow characteristics. This ensures uniform treatment across the entire cross-section while keeping each individual pipe relatively simple in design.
3Area of stationary object
If a horizontal supply pipe penetrating the chip bed is used, then distribution area is increased, but the pipe may hinder the chip plug movement
Solution Approach 1:
Instead of using a horizontal pipe that penetrates the chip bed perpendicular to the flow direction, the invention inverts the approach by using vertical pipes that are parallel to the chip plug flow direction. This inversion eliminates the obstruction problem while maintaining effective distribution area, as the pipes align with rather than cross the chip flow paths.
4Productivity
If the vessel diameter is increased to accommodate higher production rates, then productivity is improved, but the added treatment liquor may not be evenly distributed over the entire cross-sectional area
Solution Approach 1:
The distribution problem is solved by transitioning from a two-dimensional annular distribution pattern at the wall to a three-dimensional array of vertically distributed pipes throughout the vessel cross-section. This dimensional change allows treatment liquor to be delivered to all radial and axial positions within the chip plug, ensuring even distribution across large vessel diameters required for high productivity while maintaining uniform treatment quality.
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 consistent pulp quality by achieving uniform alkali distribution, reducing rejects, and minimizing steam channeling, leading to improved pulp strength properties and yield.
Implementation Method 1
a flashing effect is obtained in the chip volume being located above the liquid level in the vessel
Implementation Method 2
The temperature of the treatment liquor added via the 2 or more pipes at the position of the outlets exceeds the boiling temperature at the prevailing pressure close to the outlets
Data Source
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AI summary
The invention relates to a method and arrangement for adding treatment liquor to comminuted cellulose material, preferably wood chips, during the manufacture of chemical pulp in a continuous process. Said process using a down flow vessel where chips are descending down the vessel in a plug flow and where treated chips are continuously fed out at the bottom of the vessel. By arranging more than two parallel pipes 7b offset from the center of the vessel could a better distribution of treatment liquor be obtained, and the disturbance of the chip plug flow descending down the vessel will be reduced to a minimum.