Vacuum Condenser Steam Condensate Injection for Urea Plant Ammonia Absorption
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Solution Overview
Problem
Traditional vacuum systems in urea plants require excessive steam condensate for ammonia absorption, leading to oversizing of the water treatment section and thermodynamic penalization of the urea synthesis reaction, and are unable to efficiently transfer purge gases due to insufficient pressure.
Innovation Solution
The apparatus and method involve injecting steam condensate upstream of at least one condensation stage in the vacuum system and modifying the cooling water circuit to reduce the temperature of cooling water fed to the condensers, allowing for more efficient ammonia absorption and reducing the overall water intake, while also increasing the pressure of purge gases for treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If steam condensate is injected downstream of condensation stages for ammonia absorption, then ammonia removal is achieved, but excessive water intake occurs and water treatment section must be oversized
Solution Approach 1:
The patent applies preliminary action by injecting steam condensate upstream of the condensation stages rather than downstream. This allows the condensate to be present before the vapors pass through the condensation stages, enabling more efficient ammonia absorption in the condensed liquid phase. The preliminary positioning of the absorbent (steam condensate) ensures that ammonia is captured during the condensation process itself, rather than requiring excessive wash water downstream.
2Manufacturing precision
If vacuum concentration is performed at low pressure, then urea solution concentration is achieved, but air ingress occurs and requires purging
Solution Approach 1:
The patent converts the harmful effect of air ingress into a beneficial process feature. Instead of merely treating air ingress as a problem to be eliminated through purging, the system utilizes the presence of air and associated vapors as an opportunity to enhance ammonia absorption. The steam condensate injection upstream allows ammonia to be absorbed into the condensate along with air and vapor components, transforming the purging operation into a combined absorption and concentration process that reduces overall water consumption.
3Device complexity
If cooling water temperature is high, then condensation process is simpler, but ammonia absorption efficiency decreases
Solution Approach 1:
The patent applies parameter changes by modifying the temperature parameter of the cooling water. The system is designed to utilize cooler cooling water (lower temperature) to enhance the ammonia absorption efficiency in the steam condensate. This temperature parameter change increases the solubility and absorption capacity of ammonia in the condensate, allowing for more effective ammonia removal while maintaining system simplicity through the upstream injection approach.
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 the amount of steam condensate needed for ammonia absorption by approximately 40-45%, decreases the total water intake, and enables the transfer of purge gases to treatment systems, improving the efficiency and reducing the thermodynamic penalties of the urea synthesis reaction.
Implementation Method 1
The main function of the vacuum system is to ensure the necessary operating pressure of the upstream concentration stage by the condensation of the vapours coming therefrom
Implementation Method 2
there is a certain amount of ammonia (generally ranging between approximately 12000 mg/Nm3 and 26000 mg/Nm3) that must be reduced, both for possible environmental problems and because ammonia is a raw material
Implementation Method 3
modifying the cooling water circuit to reduce the temperature of cooling water fed to the condensers
Data Source
AI summary
An apparatus for treatment of process vapours coming from a vacuum concentration section of a urea plant, comprising a vacuum system having a plurality of successive condensation stages, connected in series by respective line portions and crossed in series by process vapours to be treated; the apparatus has at least one primary steam condensate inlet for feeding steam condensate to the vacuum system and positioned, with reference to a circulation direction of the process vapours in the vacuum system, upstream of at least one selected condensation stage, or in at least one selected condensation stage.