Urea Plant Modernization via Dual Stripping Units
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Solution Overview
Problem
Existing methods for modernizing urea production plants using the stripping process with carbon dioxide struggle to achieve high production capacity and conversion yield while minimizing energy consumption and investment costs.
Innovation Solution
The method involves adding a second stripping unit downstream the synthesis reactor, feeding a portion of the reaction mixture to each stripping unit, and directing a portion of the ammonia and carbon dioxide vapor phase from the second stripping unit directly to the synthesis reactor, allowing for substantial total condensation in the condensation unit, thus enhancing efficiency and capacity without significant upgrades to the high-pressure section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a condensation unit of the submerged type is used to increase production capacity and conversion yield, then higher efficiency is obtained, but energy consumption and investment costs increase
Solution Approach 1:
The reaction mixture flow is divided into two separate streams, with each stream processed by an independent stripping unit. This segmentation allows parallel processing without requiring a single large-scale submerged condensation unit, thereby maintaining high productivity while distributing energy consumption across multiple smaller units with better thermal efficiency
Solution Approach 2:
Instead of upgrading the condensation unit to a submerged type (vertical development), the patent adds a second stripping unit in parallel (horizontal development). This dimensional shift in system expansion strategy achieves increased production capacity without the high energy consumption associated with submerged condensation technology
2Productivity
If a condensation unit of the submerged type is installed to increase conversion yield, then higher yield is obtained, but investment costs increase
Solution Approach 1:
The patent divides the urea production process into two parallel streams, each with its own stripping unit. This segmentation allows the use of simpler, less expensive stripping technology in each unit rather than investing in a single complex submerged condensation unit, achieving high conversion yield through distributed processing
Solution Approach 2:
The outputs from two separate stripping units are merged and combined before entering the existing condensation unit. This merging strategy allows the system to achieve the conversion yield of a larger submerged unit while using multiple smaller, more cost-effective stripping units, thereby reducing overall investment costs
3Productivity
If the existing condensation unit is upgraded to submerged type, then production capacity increases, but device complexity and modification costs increase
Solution Approach 1:
The existing condensation unit is preserved and continues to serve its original function. Instead of modifying it for submerged operation, the patent makes it universal by accepting combined feeds from two different stripping units, thereby increasing production capacity without any modification to the condensation unit itself
Solution Approach 2:
The existing condensation unit operates as-is without requiring upgrades or modifications. The system achieves increased production capacity through self-service by adding parallel stripping units that feed into the existing infrastructure, eliminating the need for expensive modifications to the condensation unit
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 significantly increases production capacity and conversion yield, reduces energy consumption, and minimizes costs by allowing the existing condensation unit to operate at maximum efficiency with minimal modifications, achieving de-bottlenecking of the high-pressure section and maintaining low investment, implementation, and operation costs.
Implementation Method 1
a stripping unit with carbon dioxide for subjecting a reaction mixture comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor to a treatment of partial decomposition of carbamate and partial separation of free ammonia
Implementation Method 2
at least one condensation unit of the film type, comprising a tube bundle for subjecting to partial condensation the flow comprising ammonia and carbon dioxide in vapour phase leaving the stripping unit
Data Source
AI summary
A method for modernizing a urea production plant including a urea synthesis reactor, a stripping unit and at least one condensation unit. The method includes providing: means in the condensation unit for substantially condensing at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the stripping unit; a second stripping unit; means for feeding a first portion of a reaction mixture flow comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor to the first stripping unit; means for feeding a second portion of the reaction mixture flow leaving the reactor to the second stripping unit; and means for feeding at least a portion of a flow comprising ammonia and carbon dioxide in vapor phase leaving the second stripping unit directly to the synthesis reactor. A de-bottlenecking of the high-pressure section downstream of the synthesis reactor may be achieved, improving production capacity.