Bleaching Tower Liquid Distributor with Serrated Weir
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Solution Overview
Problem
Conventional bleaching towers in nitric acid production face challenges in achieving uniform gas-liquid contact and efficient removal of dissolved nitrogen oxides, leading to bottlenecks in nitric acid production capacity and excessive stripping gas usage.
Innovation Solution
The use of structured packing in combination with a liquid distributor featuring a serrated weir that distributes the aqueous nitric acid solution through upward-pointing serrations into perforated trays, optimizing gas-liquid contact and reducing stripping gas requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional trays or random packing are used in the bleaching tower, then the structure is simple and easy to manufacture, but the gas-liquid contact is non-uniform and the removal efficiency of dissolved nitrogen oxides is insufficient
Solution Approach 1:
The patent employs structured packing materials with high surface area and porous structure to achieve uniform gas-liquid contact throughout the tower. The structured packing provides a large effective contact area for mass transfer while maintaining a relatively simple overall tower structure, resolving the contradiction between productivity improvement and device complexity
Solution Approach 2:
The bleaching tower is divided into multiple sections with different packing types or configurations along the height of the tower. This segmentation allows optimization of gas-liquid contact in different zones while maintaining manageable structural complexity, enabling improved nitrogen oxide removal efficiency without excessive structural complexity
2Productivity
If conventional liquid distributors are used, then the device complexity is low, but the liquid distribution uniformity is poor leading to inefficient mass transfer
Solution Approach 1:
The liquid distributor is designed with locally optimized features such as varied hole sizes, non-uniform spacing, or different opening angles in different regions to compensate for non-uniform flow patterns. This local quality adjustment improves overall liquid distribution uniformity and mass transfer efficiency without requiring complete redesign of the entire distributor structure
Solution Approach 2:
The liquid distributor incorporates adjustable or flexible elements that can adapt to different operating conditions and flow rates. This dynamic design allows the distributor to maintain effective liquid distribution across a range of production capacities, improving productivity while keeping the structural complexity manageable through adaptability rather than fixed complex geometry
3Reliability
If more stripping gas is used to improve nitrogen oxide removal, then the removal efficiency increases, but the energy consumption and operating cost increase
Solution Approach 1:
The patent incorporates monitoring of nitrogen oxide levels in the effluent gas stream and uses this information to adjust the stripping gas flow rate dynamically. This feedback control ensures that sufficient gas is used to maintain removal efficiency while avoiding excessive gas consumption when lower stripping rates would suffice, thereby reducing energy consumption while maintaining reliability
Solution Approach 2:
The structured packing and liquid distributor design changes the mass transfer parameters (increasing surface area, improving contact efficiency) to achieve the same or better nitrogen oxide removal efficiency at lower stripping gas flow rates. This parameter optimization reduces the energy required for gas compression and circulation while maintaining removal efficiency
4Productivity
If the bleaching tower is designed for high capacity, then the production capacity increases, but the gas-liquid contact efficiency decreases
Solution Approach 1:
The structured packing introduces an additional dimensional aspect to the gas-liquid contact by creating three-dimensional flow paths and contact surfaces within the tower. This dimensional enhancement allows high capacity operation while maintaining efficient mass transfer through increased surface area and improved flow distribution in multiple directions rather than simple linear contact
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 configuration enhances nitric acid production capacity, reduces stripping gas usage, and maintains low levels of dissolved nitrogen oxides, resulting in improved acid quality and process efficiency.
Implementation Method 1
a bleaching tower for removing dissolved nitrogen oxides from an aqueous nitric acid solution comprising said nitrogen oxides, using a stripping gas substantially devoid of nitrogen oxide gases
Implementation Method 2
The aqueous nitric acid solution is contacted with the stripping gas moving in a counter-current direction to the aqueous nitric acid solution
Implementation Method 3
a liquid distributor comprising a feed box having a serrated weir for distribution of the aqueous nitric acid solution through upward-pointing serrations of the serrated weir into perforated trays
Implementation Method 4
The vertical bleaching tower comprises a structured packing; a liquid distributor comprising a feed box having a serrated weir for distribution of the aqueous nitric acid solution
Data Source
AI summary
A vertical bleaching tower for removing dissolved nitrogen oxides from an aqueous nitric acid solution using a stripping gas such as air, nitrogen, oxygen or combinations thereof in a process for producing nitric acid, comprising a structured packing; a liquid distributor comprising a feed box having a serrated weir for distribution of the aqueous nitric acid solution comprising the dissolved nitrogen oxides through upward-pointing serrations of the serrated weir into perforated trays of the liquid distributor and located above the structured packing for distributing the aqueous nitric acid solution comprising the dissolved nitrogen oxides to the structured packing; an inlet and outlet, both suitable for aqueous nitric acid solution; and an inlet and outlet, both suitable for the stripping gas. The present invention further comprises a bleaching method for removing dissolved nitrogen oxides from an aqueous nitric acid solution in a vertical bleaching tower.