Intermediate Pressure Section for Urea Plant Capacity Boost
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Solution Overview
Problem
Existing self-stripping urea plants face bottlenecks in the medium- and low-pressure sections when the high-pressure loop is boosted, leading to capacity issues and increased costs for revamping, as the downstream sections are often close to maximum capacity and require additional pressure vessels.
Innovation Solution
The introduction of an intermediate pressure section between the high-pressure and medium-pressure sections for additional carbamate decomposition and recovery, operating at a pressure greater than the medium-pressure section but lower than the high-pressure section, to redirect and process a portion of the urea solution, thereby alleviating the bottleneck and increasing the high-pressure section's capacity without overburdening the downstream sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the high-pressure loop capacity is boosted, then the urea production capacity is improved, but the medium- and low-pressure sections become overloaded and cannot handle the increased flow rate
Solution Approach 1:
The patent divides the original single-pressure decomposition process into two separate stages: a high-pressure decomposition section and a medium-pressure decomposition section. This segmentation allows each section to handle a portion of the carbamate decomposition load, enabling the high-pressure section to be boosted without overloading the downstream medium-pressure section.
Solution Approach 2:
The patent introduces an intermediate high-pressure decomposition section that acts as a mediator between the synthesis reactor and the original medium-pressure section. This intermediate section processes a portion of the carbamate decomposition at high pressure, reducing the burden on the downstream medium-pressure section and allowing independent capacity optimization.
2Productivity
If the medium- and low-pressure sections are revamped to handle increased capacity, then the bottleneck is removed, but the cost increases significantly due to adding or replacing pressure vessels
Solution Approach 1:
By segmenting the decomposition process into high-pressure and medium-pressure sections, the patent avoids the need to completely revamp the medium-pressure section. Instead, a new high-pressure decomposition section is added, which can be integrated more economically than replacing existing medium-pressure pressure vessels.
Solution Approach 2:
The patent adds a new dimension to the process by introducing a high-pressure decomposition stage that operates at a different pressure level than the existing medium-pressure section. This dimensional change in pressure levels allows capacity expansion without directly modifying the existing medium-pressure equipment.
3Productivity
If the high-pressure stripper processes more carbamate, then more ammonia is recovered, but the medium-pressure section cannot handle the increased ammonia recovery duty
Solution Approach 1:
The patent segments the ammonia recovery function across two pressure levels: high-pressure ammonia recovery in the new decomposition section and medium-pressure ammonia recovery in the existing section. This segmentation allows each section to operate within its optimal capacity range while collectively handling the total ammonia recovery duty.
Solution Approach 2:
The high-pressure decomposition section serves as an intermediary that performs preliminary ammonia recovery before the medium-pressure section. This intermediate recovery step reduces the ammonia load on the downstream medium-pressure section, allowing both sections to operate efficiently.
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 allows for a significant boost in the high-pressure section capacity while maintaining the duty of the downstream medium- and low-pressure sections, reducing the need for costly upgrades and enhancing the overall efficiency of the urea plant processing.
Implementation Method 1
a further step of carbamate decomposition and carbamate recovery is added upstream the MP section
Implementation Method 2
a vapour phase containing ammonia and CO 2 produced in the stripper is condensed in the high-pressure condenser
Implementation Method 3
a steam-heated stripper
Implementation Method 4
heated in the high-pressure stripper to decompose the carbamate and recover ammonia
Data Source
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AI summary
A method for revamping a self-stripping urea plant is disclosed, where an intermediate recovery section (30) is installed between the existing high- pressure section and medium-pressure section; a stream of urea solution (15A), which is delivered by the high pressure section, is directed to said intermediate section (30), and a flow of concentrated solution (15B) from said intermediate section is directed to said medium pressure section, the intermediate section operating at a pressure between those of the high- and medium-pressure sections. A related process and plant are also disclosed.