UAN Production Condensing Off-Gas to Reduce Water and Steam
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Solution Overview
Problem
Current UAN production processes face challenges in reducing steam consumption, emissions, especially ammonia, waste streams, and make-up water usage, while also aiming to improve energy efficiency and product recovery, particularly in existing plants where equipment costs are a concern.
Innovation Solution
The process involves condensing ammonia-containing off-gas under acidic conditions to form an acidic condensate, which is used as a scrubbing liquid to treat ammonia-containing off-gas, reducing the need for make-up water and allowing for higher UAN production by recycling scrubbing liquid and recovering ammonium nitrate and urea from off-gas, thus minimizing nitric acid consumption and adjusting UAN solution concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional UAN production processes are used, then ammonium nitrate and urea are produced and combined, but steam consumption is high and energy efficiency is low
Solution Approach 1:
The process recovers ammonia from off-gas streams generated during UAN production and reinjects it into the ammonium nitrate synthesis section. This recovery and reuse of ammonia eliminates the need for additional fresh ammonia production, reducing steam consumption and improving energy efficiency by converting what would be waste into a valuable resource.
Solution Approach 2:
The system implements a feedback loop where off-gas containing ammonia is captured, condensed, and the condensate is recycled back to the ammonium nitrate synthesis section. This closed-loop feedback mechanism maintains ammonia availability for production while minimizing emissions and reducing the need for additional energy-intensive ammonia synthesis.
2Object-generated harmful factors
If conventional scrubbing methods are used to treat off-gas, then ammonia emissions are reduced, but make-up water usage increases
Solution Approach 1:
Instead of discarding the scrubbing liquid after use, the process recycles it back to the ammonium nitrate synthesis section. The scrubbing liquid, which contains dissolved ammonia and nitric acid, is reused as feed material for ammonium nitrate production, eliminating the need for continuous make-up water while maintaining effective emission control.
Solution Approach 2:
The scrubbing liquid serves multiple functions: it acts as an emission control medium in the scrubbing section, and then as feed material for ammonium nitrate synthesis in the production section. This multi-functionality maximizes the utility of the liquid stream, reducing waste and make-up water requirements.
3Object-generated harmful factors
If off-gas is condensed and scrubbed with fresh water, then ammonia is removed from emissions, but nitric acid consumption increases
Solution Approach 1:
The process recovers nitric acid from the scrubbing liquid and reinjects it into the ammonium nitrate synthesis section. This recovery prevents nitric acid loss and reduces the need for fresh nitric acid makeup, while the scrubbing liquid is reused as feed material rather than being discarded.
Solution Approach 2:
A feedback loop is established where the scrubbing liquid containing nitric acid is recycled back to the ammonium nitrate synthesis section. This feedback mechanism ensures that nitric acid is not lost but rather reused in the production process, minimizing external nitric acid consumption.
4Loss of substance
If separate treatment sections are added for liquid recycle streams, then product recovery improves, but device complexity and capital expenditure increase
Solution Approach 1:
The process merges the liquid recycle stream treatment with the existing ammonium nitrate synthesis section by reinjecting the scrubbing liquid directly into it. This integration eliminates the need for separate treatment equipment while maintaining effective product recovery, as the scrubbing liquid serves as feed material for ammonium nitrate production.
Solution Approach 2:
The ammonium nitrate synthesis section serves dual functions: it produces ammonium nitrate product and simultaneously processes the scrubbing liquid recycle stream. This multi-functionality reduces the need for dedicated treatment equipment, lowering capital expenditure and device complexity while maintaining effective product recovery.
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 reduces make-up water usage by up to 50%, enhances energy efficiency, and allows for higher UAN production with reduced nitric acid consumption and waste management, while avoiding the need for separate treatment of liquid recycle streams, thus lowering operational costs.
Implementation Method 1
subjecting ammonia-containing off-gas of the finishing section to condensation under acidic conditions so as to form an acidic condensate
Implementation Method 2
a finishing section adapted to solidify urea liquid
Implementation Method 3
using at least part of the acidic condensate as an acidic scrubbing liquid in a finishing treatment section adapted to subject ammonia-containing off-gas of the finishing section to treatment with an acidic scrubbing liquid
Data Source
AI summary
The invention relates to a process for the production of urea ammonium nitrate, a system and a method of modifying a plant. The process comprises subjecting ammonia-containing off-gas resulting from the production of ammonium nitrate (AN off-gas) to condensation under acidic conditions so as to form an acidic condensate, and using at least part of the acidic condensate as an acidic scrubbing liquid in a finishing treatment section having a gas inlet in fluid communication with a gas outlet of a finishing section of a urea production unit, wherein the finishing section is adapted to solidify urea liquid, and wherein said finishing treatment section is adapted to subject ammonia-containing off-gas of the finishing section to treatment with an acidic scrubbing liquid.