Wash Tower Cooling Loop for Higher Ammonia Absorption
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Solution Overview
Problem
Urea-producing plants face the challenge of improving the efficacy of wash towers used to remove ammonia from gas streams while minimizing costs and disrupting the overall plant operations.
Innovation Solution
Incorporating a heat exchanger into the wash tower system to cool the aqueous solution recovered from the wash tower, which is then re-injected to enhance ammonia absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the aqueous solution is cooled before re-injection, then ammonia absorption efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by cooling the aqueous solution before re-injection to shift the absorption equilibrium. By changing the temperature parameter of the liquid phase, the system improves ammonia absorption efficiency without requiring additional absorption stages or larger equipment, thus enhancing productivity while controlling energy input.
Solution Approach 2:
The patent utilizes phase transition principles by cooling the aqueous solution to change its thermal state, which affects the solubility equilibrium of ammonia in water. The temperature reduction causes a shift in the phase equilibrium, increasing the driving force for ammonia absorption from gas phase to liquid phase, thereby improving removal capacity.
2Productivity
If more aqueous solution is used for absorption, then ammonia removal efficiency improves, but water consumption increases
Solution Approach 1:
The patent implements discarding and recovering by continuously recycling the aqueous solution from the liquid outlet back to the liquid inlet after cooling. This closed-loop approach recovers the water that has absorbed ammonia, cools it to restore absorption capacity, and reuses it, thereby maintaining high removal efficiency while minimizing net water consumption.
Solution Approach 2:
The system applies feedback control by continuously circulating and cooling the aqueous solution. The cooled solution is fed back to the absorption zone, creating a sustained concentration gradient that drives efficient ammonia removal. This feedback mechanism allows the system to maintain optimal performance with minimal water input.
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
Enhances the ammonia removal capacity of the wash tower by shifting the equilibrium towards absorption, reducing water consumption, and maintaining operational efficiency with minimal additional costs.
Implementation Method 1
the system further comprises a heat exchanger, wherein the heat exchanger is fluidly connected to the at least one liquid inlet and the liquid outlet, and the heat exchanger is configured for cooling down the aqueous solution comprising ammonia recovered from the liquid outlet
Implementation Method 2
one or more absorption elements or absorption sections located between the gas inlet and the gas outlet, wherein a gas stream comprising ammonia is injected at the bottom of the wash tower and travels through the at least one absorption element where it comes into contact with liquid water or a liquid aqueous solution, which absorbs the ammonia comprised in the gas streams
Data Source
Figure 1
Figure 1
AI summary
The present disclosure provides a system comprising a wash tower and a heat exchanger for cooling an aqueous solution. The present disclosure also provides a method for removing ammonia from a gas stream.