Integrated Carbamate Condenser-Stripper for Low-Biuret Urea
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing urea production processes face challenges in achieving good energy efficiency and low biuret content in the produced urea.
Innovation Solution
A process and plant design involving a high-pressure synthesis section with a carbamate condenser and stripper, utilizing a shell-and-tube heat exchanger with horizontal tube bundles, includes condensation, expansion, and evaporation stages to decompose carbamate, control N/C ratio, and utilize steam for heating, minimizing biuret formation and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional urea production processes are used, then energy efficiency is insufficient, but increasing energy consumption to improve efficiency creates a contradiction
Solution Approach 1:
The patent combines the carbamate condenser and stripper into a single integrated unit, allowing heat exchange between the condensing carbamate stream and the stripper feed. This integration enables energy recovery where the heat from condensing carbamate is used to preheat the stripper feed, reducing overall energy consumption while maintaining efficient operation.
Solution Approach 2:
The patent operates the carbamate condenser at elevated pressures (50-200 bar) and temperatures (80-150°C) to optimize the phase behavior and heat exchange efficiency. By controlling pressure and temperature parameters, the system achieves better energy efficiency in carbamate condensation and reduces energy losses in the overall process.
2Object-generated harmful factors
If conventional carbamate condensation is used, then biuret content in produced urea is high, but reducing biuret formation requires process modifications that increase complexity
Solution Approach 1:
The patent performs preliminary decomposition of carbamate in the carbamate condenser before the stripper by controlling temperature and pressure conditions. This preliminary action reduces the carbamate load entering the stripper and minimizes biuret formation in subsequent evaporation stages, achieving low biuret content without adding complex equipment.
Solution Approach 2:
The integrated carbamate condenser-stripper system acts as an intermediary that controls the decomposition and removal of carbamate before it can convert to biuret. The heat exchange between condensing carbamate and stripper feed creates optimal conditions for carbamate decomposition while preventing excessive temperature rises that would promote biuret formation.
3Volume of stationary object
If equipment size is reduced to save space and cost, then heat exchange efficiency decreases, but maintaining efficiency with larger equipment increases investment
Solution Approach 1:
The patent segments the carbamate condenser into multiple sections with different heat exchange configurations. The first section handles high-temperature carbamate condensation while the second section recovers heat at lower temperatures. This segmentation allows efficient heat exchange in a compact overall volume by optimizing each section for its specific function.
Solution Approach 2:
The patent employs a nested heat exchanger configuration where heat exchange surfaces are arranged concentrically or in nested patterns. This allows maximum heat transfer surface area within minimum equipment volume, achieving high heat exchange efficiency without requiring large equipment size.
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
The process achieves high urea content and low biuret levels while reducing energy consumption and equipment size, enhancing safety and efficiency in urea production.
Implementation Method 1
condensing gas from the stripper in the shell space thereby providing a carbamate-containing high pressure liquid stream
Implementation Method 2
heating said first MP urea solution in said first tube bundle, thereby decomposing said carbamate comprised in said first MP urea solution
Implementation Method 3
condensing said MP gas stream at medium pressure in a first condensation compartment thereby forming carbamate
Implementation Method 4
heating through indirect heat exchanging contact a urea solution to be heated giving a heated urea solution in a first evaporation stage
Implementation Method 5
raising steam in said second tube bundle
Implementation Method 6
using said steam to further heat through indirect heat exchanging contact said heated urea solution in a second evaporation stage
Data Source
AI summary
The disclosure pertains to a urea production process wherein carbamate in a medium pressure (MP) urea solution is decomposed in a tube bundle of a high pressure (HP) carbamate condenser and resulting gas is condensed in indirect heat exchange with urea solution to be heated and wherein a high pressure (HP) stripper is preferably operated with relatively low stripping efficiency.