Urea Synthesis Forced Circulation Layout
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Solution Overview
Problem
The existing high pressure loop for urea production, which relies on a vertical layout of the synthesis reactor, stripper, and condenser, faces limitations in increasing production capacity without disrupting natural circulation and incurs high construction and maintenance costs due to the need for complex safety structures and vertical reactor placement.
Innovation Solution
Implementing a forced circulation process by pumping the reaction mixture between the synthesis reactor and stripper, allowing variation of production capacity through pressure and flow rate adjustments, and enabling a horizontal layout where the reactor and stripper are at the same level, thus eliminating the need for complex safety structures and allowing increased production without altering the plant layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a vertical layout is used for the synthesis reactor and stripper to maintain natural circulation, then the high pressure loop can operate with pressure differences generated by phase variations, but the production capacity cannot be increased without disrupting the circulation balance and requiring complex safety structures
Solution Approach 1:
The patent replaces the natural circulation system (which relies on gravitational forces and pressure differences generated by phase changes) with a forced circulation system using a pump. This substitution eliminates the need for vertical reactor placement and complex safety structures, allowing horizontal layout and increased production capacity without disrupting circulation balance
Solution Approach 2:
The patent changes the circulation mode from natural (passive) to forced (active) by introducing a pump, which allows independent control of flow rate and pressure. This parameter change enables the system to operate at higher production capacities while maintaining circulation stability, and allows the reactor to be placed horizontally rather than vertically
2Reliability
If the synthesis reactor is raised to a higher level to enable vertical layout, then natural circulation can be maintained, but construction costs and maintenance costs increase due to the need for complex safety structures
Solution Approach 1:
The patent replaces the gravity-based natural circulation system with a pump-driven forced circulation system. This eliminates the need to raise the reactor to a higher level and construct complex safety structures, thereby reducing both construction and maintenance costs while maintaining circulation reliability through active control
3Productivity
If the production capacity of the synthesis reactor is increased, then more urea can be produced, but the natural circulation balance is disrupted and the pressure difference of 1 bar is no longer sufficient to counteract pressure drops
Solution Approach 1:
The patent changes the circulation control from passive (relying on fixed pressure differences) to active (using a pump with adjustable parameters). This allows the system to maintain circulation balance at increased production capacities by adjusting pump flow rate and pressure to match the higher demand, overcoming the limitation of the fixed 1 bar pressure difference in natural circulation systems
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 flexible and cost-effective expansion of urea production capacity, reduces investment and maintenance costs, and improves safety by enabling a horizontal layout that maintains high-pressure loop efficiency without the need for complex vertical reactor structures.
Implementation Method 1
the said reaction mixture obtained from the reaction between ammonia and carbon dioxide is pumped to the operative steps of decomposition and stripping
Implementation Method 2
operative steps of decomposition of the ammonium carbamate into NH3 and CO2
Implementation Method 3
subsequent operative step of their recondensation (partial or total) into ammonium carbamate
Data Source
AI summary
A process for urea production from ammonia and carbon dioxide, made to react at a predetermined high pressure in an appropriate synthesis reactor (112), from the reaction between NH3 and CO2 being obtained a reaction mixture comprising urea, ammonium carbamate and free ammonia in aqueous solution, from which a recovery of ammonium carbamate and ammonia is carried out with their subsequent recycle to the synthesis reactor (112), said recovery from the reaction mixture taking place through operative steps of decomposition of the ammonium carbamate into NH3 and CO2 and of their stripping and a subsequent operative step of their recondensation into ammonium carbamate that is recycled to the synthesis reactor, the said reaction mixture obtained from the reaction between ammonia and carbon dioxide being pumped to the operative steps of decomposition and stripping.