Sulfuric Acid Concentrator Column with Recirculation Loop
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Solution Overview
Problem
Existing sulfuric acid concentration processes, such as the Integrated Sulfuric Acid Concentrator (ISAC), struggle to achieve the desired concentration of 98 wt% sulfuric acid due to limitations in sulfuric acid concentrating capacity, flexibility, and energy requirements, especially when dealing with wet-type sulfuric acid plants.
Innovation Solution
A process that involves stripping water from already concentrated sulfuric acid using a stripping medium like air or process gas in a sulfuric acid concentrator column, with a fraction of the acid being recycled back through an acid recirculation loop to adjust concentration, temperature, and flow rates, allowing for flexible operation and increased concentration up to 98 wt%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ISAC unit is used to increase sulfuric acid concentration, then the acid concentration can be improved from 93 wt% to approximately 96.3 wt%, but the concentrating capacity is limited by the allowable flow of hot dried air
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary device between the acid feed stream and the hot dried air stream. This heat exchanger preheats the acid feed before it enters the ISAC column, improving the efficiency of the concentration process and enabling higher concentrating capacity without increasing the hot dried air flow beyond allowable limits.
Solution Approach 2:
The patent changes the temperature parameter of the acid feed by preheating it in the heat exchanger. This parameter change allows the acid to enter the ISAC column at a higher temperature, improving the mass transfer efficiency and enabling the system to achieve the desired concentration with the available hot dried air flow, thus increasing concentrating capacity.
2Manufacturing precision
If multiple distillation steps are used to reach acid concentration above 98.0 wt%, then the manufacturing precision is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The patent applies preliminary action by preheating the acid feed in a heat exchanger before it enters the ISAC column. This preliminary heating step prepares the acid for more efficient concentration in a single pass, eliminating the need for multiple distillation steps while achieving the desired concentration above 98.0 wt%.
Solution Approach 2:
The patent implements continuous useful action by using the hot dried air stream continuously to strip water from the acid in the ISAC column, combined with continuous preheating of the acid feed. This continuous process achieves high concentration in a single integrated unit rather than requiring multiple discrete distillation steps.
3Manufacturing precision
If cold dilute acid is indirectly heated to near boiling point for distillation, then the sulfuric acid concentration can be increased, but the energy consumption increases
Solution Approach 1:
The patent merges the heating function with the concentration process by using a heat exchanger that utilizes the hot dried air stream (already at elevated temperature from the ISAC process) to preheat the acid feed. This combines two functions—heating and concentration—into an integrated system, reducing overall energy consumption compared to separate indirect heating and distillation steps.
Solution Approach 2:
The system uses its own hot dried air stream, which is already heated for the concentration process, to serve the additional function of preheating the acid feed. This self-service approach recovers heat within the system rather than requiring external energy input for separate heating, thereby reducing overall energy consumption.
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 significantly enhances sulfuric acid concentrating capacity, improves operational flexibility, and reduces energy requirements, enabling the production of 98 wt% sulfuric acid independently of the initial concentration, while maintaining robust and flexible operation.
Implementation Method 1
stripping water from the sulfuric acid by contacting it with a stripping media selected from air and process gas in a sulfuric acid concentrator column
Implementation Method 2
the acid is optionally heated by heat exchange during its passage through the acid recirculation loop
Implementation Method 3
sulfuric acid condenses from the gas phase by direct or indirect cooling of the process gas containing sulfuric acid and water vapor
Data Source
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AI summary
In a process for increasing the sulfuric acid concentration of 90-98 wt% sulfuric acid, comprising stripping water from the sulfuric acid by contacting it with hot stripping media in a sulfuric acid concentrator column to increase the concentration of the acid leaving the column, the concentration of the acid is increased further by recycling a fraction of the acid, which is leaving the column, through an acid recirculation loop back to the inlet of the column, and the acid is optionally heated during its passage through the acid recirculation loop.