Ammonium Carbamate Composition Analysis via Density and Viscosity
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Solution Overview
Problem
Conventional methods fail to accurately and timely specify the composition of aqueous ammonium carbamate solutions from unreacted-gas absorber outlet liquids in urea production processes, leading to suboptimal operating conditions and increased energy consumption.
Innovation Solution
A method utilizing correlations between viscosity, temperature, and carbon dioxide concentration, and density, temperature, and ammonia concentration to determine the composition of aqueous ammonium carbamate solutions, allowing real-time measurement of ammonia, carbon dioxide, and water concentrations using oscillation-type sensors, thereby optimizing water flow rates and operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the amount of water fed to the absorber is reduced to minimize water usage, then water consumption is reduced, but the equilibrium temperature of the outlet liquid may be lower than the operating temperature, lowering absorption performance and causing loss of ammonia and carbon dioxide
Solution Approach 1:
The patent implements real-time monitoring of the outlet liquid composition through density and viscosity measurements, which are used to calculate the equilibrium temperature. This feedback mechanism allows continuous adjustment of water feed rate to maintain optimal absorption performance while minimizing water consumption. The system dynamically responds to changes in solution composition to prevent ammonia and carbon dioxide loss.
Solution Approach 2:
The patent utilizes changes in physical parameters (density and viscosity) of the outlet liquid to determine its composition and equilibrium temperature. By monitoring these parameter changes, the system can accurately assess the impact of water feed rate on absorption performance and adjust operating conditions to maintain the equilibrium temperature above the operating temperature, ensuring reliable absorption while reducing water usage.
2Reliability
If the operating temperature is decreased to improve absorption performance, then absorption efficiency is improved, but the operating temperature may be lower than the solidification temperature, causing the recovered liquid to solidify and making continuous operation impossible
Solution Approach 1:
The system continuously monitors the outlet liquid composition through density and viscosity measurements to calculate the equilibrium temperature and solidification temperature. This feedback allows real-time adjustment of the operating temperature to maintain it above the solidification temperature while keeping it below the equilibrium temperature, ensuring both absorption performance and continuous operability.
Solution Approach 2:
The patent employs real-time measurement of physical parameters (density, viscosity, temperature) to dynamically determine the equilibrium and solidification temperatures of the outlet liquid. By monitoring these parameter changes, the system can adjust operating temperature to maintain the relationship: solidification temperature < operating temperature < equilibrium temperature, preventing solidification while ensuring absorption efficiency.
3Measurement precision
If conventional analysis methods are used to measure solution composition, then measurement capability is provided, but the analysis is not real-time and requires complex procedures with time lag
Solution Approach 1:
The patent replaces conventional chemical analysis methods with physical measurement methods using density and viscosity sensors. These physical measurements provide real-time composition data without the time lag associated with chemical analysis procedures. The oscillation-type density meter and viscometer enable continuous monitoring of solution composition, eliminating the need for complex, time-consuming laboratory analysis.
Solution Approach 2:
The system uses the outlet liquid itself as the measurement medium, requiring no sample preparation, dilution, or complex handling. The density and viscosity measurements are performed directly on the flowing solution, making the analysis self-service and real-time. The system leverages the liquid's own physical properties for characterization, eliminating external intervention and time lag.
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
Enables real-time specification of solution composition, optimizing water usage and energy efficiency in urea production by determining the minimum water flow required, improving urea synthesis rates and reducing steam consumption.
Implementation Method 1
simultaneously measuring density, temperature and viscosity of the aqueous solution with an oscillation-type density meter, a thermometer and a viscometer
Implementation Method 2
simultaneously measuring density, temperature and viscosity of the aqueous solution with an oscillation-type density meter, a thermometer and a viscometer
Implementation Method 3
simultaneously measuring density, temperature and viscosity of the aqueous solution with an oscillation-type density meter, a thermometer and a viscometer
Implementation Method 4
An outlet liquid from the absorption section (unreacted-gas absorber outlet liquid) is returned to the synthesis section 31 as a recovered liquid
Data Source
Figure 1
Figure 2(a)~2(e)
Figure 3
AI summary
There are provided a method for analyzing an aqueous ammonium carbamate solution whereby the composition of an unreacted-gas absorber outlet liquid can be specified in real time, and a method for operating an unreacted gas absorber by use of the same. The method for analyzing the composition of an aqueous ammonium carbamate solution includes determining ammonia component concentration, carbon dioxide component concentration, and water concentration of the aqueous ammonium carbamate solution, which is the unreacted-gas absorber outlet liquid in a urea production process, by using a correlation among viscosity, temperature, and carbon dioxide component concentration of the aqueous solution and a correlation among density, temperature, ammonia component concentration, and carbon dioxide component concentration of the aqueous solution, wherein the ammonia component concentration is a concentration of a sum of free ammonia and equivalent ammonia of ammonium carbamate which are contained in the aqueous solution, and the carbon dioxide component concentration is a concentration of equivalent carbon dioxide of ammonium carbamate contained in the aqueous solution.