Urea Plant Medium-Pressure Condenser Capacity Expansion
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Solution Overview
Problem
Urea plants face limitations in capacity expansion due to bottlenecks in the high-pressure section, particularly in the stripper and condenser, leading to inefficiencies and the inability to utilize increased steam pressure effectively, making it difficult to increase production without modifying expensive equipment.
Innovation Solution
The implementation of a medium-pressure condenser at 0.5-12 MPa, which condenses gases from the high-pressure synthesis section and incorporates a carbamate stream from a recovery section, allowing part of the condensate to be returned to the high-pressure condenser, thereby increasing condensation capacity without enlarging the high-pressure condenser and maintaining steam pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the liquid load of the stripping zone is increased to increase capacity, then the throughput of process streams increases, but the stripping effect is lost due to flooding
Solution Approach 1:
The invention divides the condensation process into two pressure stages: a high-pressure condensation stage (10-50 bar) and a low-pressure condensation stage (1-10 bar). This segmentation allows the high-pressure stripper to operate at increased liquid loads without flooding, as the condensation burden is shared between two stages. The high-pressure condenser handles initial condensation while the low-pressure condenser completes the process, preventing overload at any single stage.
2Productivity
If the feed of gas to be condensed is increased to increase capacity, then the throughput increases, but the steam pressure becomes too low to be usable
Solution Approach 1:
The condensation process is segmented into two pressure zones. The high-pressure condenser (10-50 bar) maintains steam pressure at usable levels for plant operations, while the low-pressure condenser (1-10 bar) handles the remaining condensation load. This allows increased gas feed rates without compromising the pressure quality of generated steam.
Solution Approach 2:
The invention introduces an intermediary pressure stage between the high-pressure synthesis section and the low-pressure recovery section. The high-pressure condenser acts as an intermediary that maintains pressure levels suitable for steam utilization, bridging the gap between high-pressure synthesis and low-pressure recovery operations.
3Productivity
If the high-pressure condenser is enlarged to increase condensation capacity, then the condensation capacity increases, but the investment cost increases
Solution Approach 1:
Instead of enlarging the high-pressure condenser, the invention segments the condensation function into two separate condensers operating at different pressures. The existing high-pressure condenser operates at its original size and pressure range (10-50 bar), while a new low-pressure condenser (1-10 bar) handles the additional capacity requirement, avoiding the high cost of enlarging high-pressure equipment.
Solution Approach 2:
The invention changes the pressure parameter of the condensation process by operating one condenser at high pressure (10-50 bar) and another at low pressure (1-10 bar). This parameter change allows capacity expansion without requiring high-pressure equipment to be enlarged, significantly reducing investment costs.
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 20-40% capacity increase in urea plant production with minimal investment, maintaining reactor conversion efficiency and enabling controlled steam pressure for effective use in the low-pressure sections.
Implementation Method 1
gases leaving the high-pressure synthesis section are condensed in a medium-pressure condenser at 0.5-12 MPa
Implementation Method 2
to which also a carbamate stream from one of the recovery sections is supplied
Data Source
AI summary
The invention relates to a process for the preparation of urea from ammonia and carbon dioxide in a urea plant that contains a high-pressure synthesis section and one or more recovery section(s) at a lower pressure, the high-pressure synthesis section comprising a reactor, a stripper and a condenser, with gases leaving the high-pressure synthesis section being condensed in a medium-pressure condenser at 0.5-12 MPa to which also a carbamate stream from one of the recovery sections is supplied, after which at least a part of the formed condensate is supplied to the high-pressure condenser.