Integrated Urea Production for Low-Biuret DEF and UAN
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Solution Overview
Problem
Existing urea production processes face challenges in producing Diesel Exhaust Fluid (DEF) and Urea Ammonium Nitrate (UAN) efficiently, as they require significant investment, energy, and result in high biuret content, ammonia emissions, and inefficient use of ammonia, leading to environmental and economic inefficiencies.
Innovation Solution
Integrate the production of DEF and UAN by recycling ammonia and carbon dioxide from the urea production process to form ammonium nitrate, eliminating the need for evaporation and wastewater treatment, and optimizing biuret formation through temperature and pressure control, using a submerged condenser/reactor to produce a low biuret urea solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional urea production process is used to produce DEF, then solid urea product is obtained, but significant investment in finishing technology is needed and biuret content exceeds specification
Solution Approach 1:
The invention extracts the problematic finishing section from the conventional urea production process. Instead of producing solid urea and then dissolving it, the process directly produces aqueous urea solution from the recovery section, eliminating the need for evaporation, granulation, and dissolution steps that generate biuret and require complex finishing technology.
Solution Approach 2:
The invention inverts the conventional approach by not removing water to make solid urea and then adding water back for DEF production. Instead, it maintains the aqueous phase throughout and directly utilizes the recovery section output as DEF, reversing the typical evaporation-dissolution sequence.
2Quantity of substance
If evaporation section is used to concentrate urea, then water is removed and energy is consumed, but large amounts of water are later added during dissolution requiring significant energy
Solution Approach 1:
The invention maintains continuous useful action by keeping the urea solution in aqueous phase throughout the process. The recovery section continuously produces DEF-specification aqueous solution without interruption for evaporation and subsequent dissolution, eliminating the cyclic energy consumption of water removal and addition.
Solution Approach 2:
The invention converts what would normally be waste water (from the recovery section) into the desired product medium. Instead of treating water removal as necessary for urea production, the process embraces the aqueous output and directly utilizes it as DEF, turning a potential waste stream into the product's beneficial feature.
3Object-generated harmful factors
If ammonia is removed in scrubber and sent to wastewater treatment, then ammonia emissions are controlled, but very costly and energy intensive operation is required
Solution Approach 1:
The invention makes the system self-sufficient by using the ammonia-rich stream from the recovery section as direct feed for DEF production. The process self-regulates ammonia content through the equilibrium in the recovery section, eliminating the need for external scrubbing and wastewater treatment facilities.
Solution Approach 2:
Instead of discarding ammonia through costly scrubbing and wastewater treatment, the invention recovers and utilizes the ammonia-rich stream from the recovery section as the basis for DEF production. The ammonia is recovered as a valuable component of the final product rather than treated as waste.
4Ease of operation
If solid urea is dissolved in demineralized water to produce DEF, then solution is obtained, but significant investment in urea finishing technology is needed
Solution Approach 1:
The invention merges the urea production and DEF formulation steps into a single integrated process. The recovery section simultaneously produces concentrated urea solution and controls ammonia content, combining functions that would otherwise require separate finishing and dissolution operations.
Solution Approach 2:
The recovery section is given multi-functionality, serving both to concentrate urea from the synthesis section and to produce DEF-specification aqueous solution with controlled ammonia content. This single unit performs multiple functions that would traditionally require the entire finishing section plus dissolution equipment.
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
Achieves a low biuret content of 0.01-0.3% in DEF, increasing NOx capture efficiency by 20%, reducing raw material use by 1%, and eliminating capital investment in evaporation and wastewater treatment, while allowing flexible production to meet market demands.
Implementation Method 1
using a submerged condenser/reactor to produce a low biuret urea solution
Implementation Method 2
using a submerged condenser/reactor to produce a low biuret urea solution
Implementation Method 3
In the recovery section followed by an evaporation section. Therein the urea concentration is further increased by the evaporation of water
Implementation Method 4
By treatment in a scrubber the ammonia is removed
Data Source
AI summary
Disclosed is a method for the integrated production of two different urea products. One is an aqueous urea solution suitable for use in NOx abatement (generally indicated as Diesel Exhaust Fluid DEF). The other is a solution used as a fertilizer, viz. Urea Ammonium Nitrate (UAN). The production of DEF and UAN are integrated as follows: ammonia recovered from the production of urea is used as a feed to the production of ammonium nitrate. At least part of an aqueous urea stream from urea production, is mixed with ammonium nitrate so as to obtain UAN.