Urea Hydrolyzer Load Reduction via Segmented Stripping
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Solution Overview
Problem
Existing urea production technologies require high amounts of heating steam and result in ammonia emission into the atmosphere due to the high load on urea hydrolyzers and the inefficiency in separating ammonia and carbon dioxide, which complicates the equipment design and operation.
Innovation Solution
A treatment method that involves introducing an aqueous solution containing urea, ammonia, and carbon dioxide into a first stripper for separation, followed by hydrolysis in a urea hydrolyzer under pressure, and subsequent separation in a second stripper, with a portion of the solution being diverted to an exhaust gas treatment equipment equipped with a urea dust scrubbing and ammonia scrubbing system to reduce ammonia emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If all aqueous solution is introduced into the urea hydrolyzer for complete treatment, then urea hydrolysis efficiency is improved, but heating steam consumption and equipment load increase significantly
Solution Approach 1:
The aqueous solution treatment is divided into two segments: (1) stripping ammonia and carbon dioxide in the first stripper, and (2) hydrolyzing only the remaining urea in the urea hydrolyzer. This segmentation allows selective treatment of different components, reducing the load on the hydrolyzer and heating steam consumption while maintaining hydrolysis efficiency for the remaining urea.
Solution Approach 2:
Ammonia and carbon dioxide are removed in advance through the first stripper before the aqueous solution enters the urea hydrolyzer. This preliminary action prevents these substances from interfering with the hydrolysis reaction and reduces the total amount of material that needs to be heated and processed in the hydrolyzer, thereby reducing heating steam consumption.
2Manufacturing precision
If traditional stripping and distillation methods are used to separate ammonia and carbon dioxide, then separation is achieved, but equipment complexity and operation difficulty increase
Solution Approach 1:
The first stripper integrates both stripping functions (removing ammonia and carbon dioxide) and serves as a pre-treatment unit for the urea hydrolyzer. This merging of functions into a single equipment unit simplifies the overall process flow and reduces equipment complexity compared to separate stripping and hydrolysis systems.
Solution Approach 2:
The first stripper performs multiple functions: (1) stripping ammonia from the aqueous solution, (2) stripping carbon dioxide from the aqueous solution, and (3) preparing the solution for subsequent urea hydrolysis. This multi-functionality reduces the need for separate dedicated equipment for each function, simplifying the overall system.
3Manufacturing precision
If high load is applied to the urea hydrolyzer to ensure complete urea hydrolysis, then hydrolysis efficiency is improved, but ammonia emission into atmosphere increases
Solution Approach 1:
Ammonia is extracted and removed from the aqueous solution in the first stripper before the solution enters the urea hydrolyzer. By taking out ammonia in advance, the hydrolyzer operates under lower load conditions, and any ammonia generated during hydrolysis can be more effectively controlled and prevented from atmospheric emission.
Solution Approach 2:
The ammonia that would otherwise be a harmful emission is converted into a recoverable resource by stripping it in the first stripper. This converts the harmful emission problem into a beneficial separation process, allowing ammonia to be recovered and reused while reducing the load on the hydrolyzer and subsequent emission risks.
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 reduces the load on the urea hydrolyzer and second stripper, conserves heating steam, and effectively suppresses ammonia emission into the atmosphere by utilizing a scrubbing system within the exhaust gas treatment equipment.
Implementation Method 1
an aqueous solution containing urea, ammonia and carbon dioxide is introduced into a first stripper and subjected to stripping, thereby separating and recovering ammonia and carbon dioxide in the aqueous solution
Implementation Method 2
the aqueous solution introduced into the urea hydrolyzer is heated under pressure, thereby hydrolyzing urea in the aqueous solution
Implementation Method 3
the aqueous solution introduced into the urea hydrolyzer is heated under pressure
Implementation Method 4
the aqueous solution introduced into the second stripper is subjected to stripping, thereby separating ammonia and carbon dioxide in the aqueous solution
Implementation Method 5
a part of the aqueous solution before being stripped in the first stripper, and/or, a part of the aqueous solution after being stripped in the first stripper but before being hydrolyzed in the urea hydrolyzer is introduced into an exhaust gas treatment equipment equipped with a urea dust scrubbing equipment and an equipment to suppress emission of ammonia
Data Source
AI summary
Disclosed are: a treatment method comprising (1) a step in which an aqueous solution containing urea, ammonia and carbon dioxide is introduced into a first stripper (PCS1) and subjected to stripping, and the aqueous solution after stripping is introduced into a urea hydrolyzer (UHY), (2) a step in which urea in the aqueous solution is hydrolyzed in the urea hydrolyzer (UHY), and the aqueous solution after hydrolysis is introduced into a second stripper (PCS2), (3) a step in which the aqueous solution is subjected to stripping in the second stripper (PCS2), and (4) a step in which a part of the aqueous solution before being stripped in the first stripper (PCS1), and/or, a part of the aqueous solution after being stripped in the first stripper (PCS1) but before being hydrolyzed in the urea hydrolyzer (UHY) is introduced into an exhaust gas treatment equipment equipped with an ammonia scrubbing equipment (ASCR); and a treatment equipment therefor.