Urea Plant Revamp via CO2 Stripping Agent Injection
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Solution Overview
Problem
The self-stripping urea plant process has inefficiencies in thermal stripping and ammonia removal, leading to bottlenecks in medium and low-pressure sections, making it challenging to increase capacity without significant cost and equipment modifications.
Innovation Solution
A method that directs a minor portion of the carbon dioxide feed as a stripping agent to the thermal stripping section, while the remaining portion goes to the reactor, potentially replacing or augmenting the existing condenser with a vertical submerged unit to enhance condensation capacity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If thermal stripping is used to remove ammonia from carbamate solution, then ammonia recovery is achieved, but stripping efficiency is insufficient and ammonia content in discharged solution increases
Solution Approach 1:
The patent changes the chemical parameter of the stripping process by introducing CO2 gas as a stripping agent instead of relying solely on thermal decomposition. This chemical parameter change enables more efficient ammonia removal through chemical reaction, resolving the contradiction between ammonia removal efficiency and stripping section performance
Solution Approach 2:
CO2 gas is introduced as an intermediary substance that facilitates ammonia removal through chemical reaction. The CO2 acts as a mediator that reacts with carbamate to release ammonia more efficiently than thermal stripping alone, improving both ammonia recovery and discharged solution quality
2Productivity
If plant capacity is increased to meet growing demand, then production volume increases, but existing equipment becomes a bottleneck and requires expensive replacement
Solution Approach 1:
The patent enables the existing thermal stripping section to serve a dual function: its original thermal decomposition role plus a new chemical stripping role using CO2. This self-service approach allows the existing equipment to handle increased production capacity without requiring replacement, as the enhanced stripping process extracts more ammonia from the same carbamate solution flow
Solution Approach 2:
The existing stripping section is transformed into a multi-functional unit that performs both thermal decomposition and chemical stripping operations. This universality allows the same equipment to achieve enhanced ammonia removal efficiency and support increased plant capacity without requiring additional or replaced equipment
3Productivity
If CO2 is used as a stripping agent in the thermal stripping section, then carbamate stripping efficiency improves and ammonia content reduces, but this represents a modification of the conventional self-stripping process
Solution Approach 1:
The patent segments the ammonia removal function into two distinct mechanisms: thermal decomposition (original function) and chemical stripping with CO2 (new function). This segmentation allows each mechanism to contribute optimally to ammonia removal, improving overall stripping efficiency while maintaining process flexibility
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 improves carbamate stripping efficiency, reduces ammonia content in the solution, and increases urea production without the need for expensive new equipment, effectively de-bottlenecking the plant and enhancing production capacity at a lower cost.
Implementation Method 1
a minor portion of the carbon dioxide feed is directed to the thermal stripping section, for use as a stripping agent
Implementation Method 2
a high-pressure condensing section comprising at least one horizontal condenser, condensing the vapour phase from the stripping section
Implementation Method 3
a steam-heated high-pressure stripping section, receiving said mixture and providing partial decomposition of the carbamate
Data Source
AI summary
A method for revamping a conventional self-stripping urea plant is disclosed, where a minor portion (18a) of the carbon dioxide feed is fed to the stripper (7) and used as a stripping agent. In further embodiments, another carbamate condenser is installed, or the conventional horizontal shell-and-tube carbamate condenser (6) is replaced with a vertical submerged unit.