Sulfuric Acid Plant Absorber Circulation for Continuous Operation
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Solution Overview
Problem
Existing heat recovery systems in sulfuric acid plants require shutdown when not operational, leading to reduced plant capacity if low pressure steam is not produced.
Innovation Solution
Implementing a dual mode operation in the sulfuric acid plant, where acid circulation between absorbers allows continued full-scale operation regardless of heat recovery system status, with adjusted irrigation rates and independent acid circulation systems for the 1st and 2nd stage absorbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat recovery system is not operational, then the plant must be shut down, but this reduces plant capacity and productivity
Solution Approach 1:
The acid circulation system is divided into two independent loops: a first acid circulation line with a first pump that can operate independently, and a second acid circulation line with a second pump that operates when heat recovery is active. This segmentation allows the plant to maintain full productivity even when the heat recovery system is non-operational, as the first circulation line can sustain absorption operations without interruption.
Solution Approach 2:
The system dynamically adjusts operational parameters based on heat recovery status. When heat recovery is non-operational, the first pump operates at adjusted circulation rates to maintain absorption efficiency without steam generation. When heat recovery is operational, the second pump takes over with optimized parameters for both absorption and steam generation, enabling full plant capacity utilization.
2Loss of energy
If the heat recovery system operates continuously, then energy recovery is maximized, but the system becomes vulnerable to shutdowns when the heat recovery system fails
Solution Approach 1:
The system prepares for potential heat recovery failures by maintaining a standby first acid circulation line with its dedicated pump. This redundant circulation path is kept ready and can immediately take over absorption operations if the heat recovery system fails, preventing unplanned shutdowns and ensuring operational continuity while energy recovery is maximized during normal operation.
Solution Approach 2:
The first acid circulation line acts as an intermediary backup system between the absorption towers and the heat recovery system. When heat recovery is operational, the second circulation line handles both absorption and energy recovery. When heat recovery fails, the first circulation line mediates to maintain absorption operations, bridging the gap between the failing heat recovery system and the absorption process.
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
Enables continuous operation of the sulfuric acid plant at full capacity even when the heat recovery system is not operational, maintaining plant efficiency without interruptions.
Implementation Method 1
a sulfur trioxide containing gas is supplied to an intermediate absorption system or to a final absorber to be at least partly absorbed in sulfuric acid
Implementation Method 2
The absorption of the SO3 in sulfuric acid is a strongly exothermal process, so that the acid is heated up and must be cooled again
Implementation Method 3
sulfuric acid withdrawn at the bottom of the Venturi absorber is supplied to an acid pump tank and further supplied to a shell space of the heat exchanger. Water is supplied to heat transfer elements arranged in the shell space and at least partly converted into steam by cooling the sulfuric acid
Implementation Method 4
Water is supplied to heat transfer elements arranged in the shell space and at least partly converted into steam by cooling the sulfuric acid
Data Source
Figure 1
Figure 2
AI summary
In a process for operating a plant for the production of sulfuric acid, wherein a sulfur trioxide containing gas is supplied to an intermediate absorption system or to a final absorber to be at least partly absorbed in sulfuric acid, wherein the intermediate absorption system comprises a two-stage absorption system, where in the 1st stage is a cocurrent absorber, and wherein the 2 nd stage is designed as countercurrent absorber, and wherein the plant further comprises a heat recovery system to produce low pressure steam by using the heat generated by the exothermic absorption of the sulfur trioxide in the sulfuric acid, it is provided that a) when the heat recovery system is in operation, all acid withdrawn from the 1 st stage absorber and from the 2 nd stage absorber is circulated in an acid circuit of the 1 st stage absorber, and b) when the heat recovery system is not in operation, no acid is fed to the 1 st stage absorber and the 2 nd stage absorber is fed from an independent acid circulation system.