Adiabatic Cooling Crystallization with Vapor Recompression
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Solution Overview
Problem
The existing methods for crystallization of organic compounds, such as p-xylene, are costly due to high energy consumption and facility costs, particularly in cooling and maintenance, especially when using refrigeration units with complex scraper mechanics and heat pumps, which are not economically viable.
Innovation Solution
An adiabatic cooling method involving direct introduction of a coolant into a crystallizer, pressurizing evaporated vapor with a compressor, and using an absorption condenser to condense and cool the mixture, allowing for continuous crystallization without a pressure-resistant container, thus reducing energy input and facility costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a jacket type crystallizer with refrigeration unit is used to cool the mixture solution to −30°C to −60°C, then crystallization of p-xylene can be achieved, but power cost and facility cost increase due to compressor and cooling surface scraper mechanics
Solution Approach 1:
The patent utilizes the phase transition of the coolant from liquid to vapor within the crystallizer. The coolant evaporates at low temperature to provide cooling effect, then the vapor is compressed and condensed in a heat exchanger to recover heat and regenerate the liquid coolant. This phase transition cycle eliminates the need for external refrigeration units and high-power compressors, significantly reducing power cost while maintaining the required crystallization temperature.
Solution Approach 2:
The system employs a self-sustaining coolant circulation mechanism where the evaporated coolant vapor is compressed and condensed to produce liquid coolant that automatically returns to the crystallizer. This closed-loop self-service system eliminates dependency on external refrigeration equipment and continuous high-power energy input, reducing both facility cost and power cost while maintaining effective crystallization conditions.
2Temperature
If a jacket type crystallizer with cooling surface scraper mechanics is used, then crystallization can be carried out at required temperature, but facility cost and maintenance cost increase due to complex mechanics
Solution Approach 1:
The patent extracts and eliminates the complex cooling surface scraper mechanics from the system by using a different crystallizer design that does not rely on jacket-type cooling with rotating scrapers. Instead, the invention uses direct evaporation of coolant within the crystallizer followed by external compression and condensation, removing the need for mechanical scraping components and simplifying the overall device structure.
Solution Approach 2:
The patent replaces the mechanical cooling surface scraper system with a thermal field-based approach. Instead of using mechanical scrapers to remove crystals from cooling surfaces, the system allows crystals to form and be handled through fluid dynamics and gravity-driven slurry movement, eliminating complex mechanical components and reducing maintenance requirements.
3Temperature
If high-pressure compression of evaporated coolant vapor is performed to enable condensation, then cooling effect is maintained, but energy input and operating cost increase
Solution Approach 1:
The patent optimizes the compression ratio and operating pressure parameters of the coolant vapor compression process. By carefully selecting the condensation temperature and corresponding pressure, the system achieves effective cooling with minimal compression work. The heat exchanger is designed to maximize heat transfer efficiency during condensation, allowing the system to maintain required cooling effects while minimizing energy input for vapor compression.
Solution Approach 2:
The system leverages the latent heat of condensation of the coolant vapor to provide the cooling effect. The phase transition from vapor to liquid in the heat exchanger releases significant heat that can be used to pre-cool the incoming mixture solution or for other process heating needs, thereby reducing the net energy input required for the overall cooling process and improving overall energy efficiency.
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 method enables efficient crystallization of organic compounds like p-xylene with reduced running and facility costs by minimizing energy consumption and eliminating the need for expensive refrigeration units, while maintaining effective crystallization processes.
Implementation Method 1
pressurizing evaporated vapor to a pressure higher than the operation pressure in the crystallizer by a compressor, introducing the pressurized coolant vapor to an absorption condenser, removing the heat of absorption and condensation
Implementation Method 2
carrying out adiabatic cooling, as for crystallization operation of target organic compound and evaporation operation of a coolant which is directly introduced in crystallizer for a mixture solution of a target organic compound containing the coolant
Implementation Method 3
heat of crystallization is taken away in association with evaporation of substantially only the liquid coolant component
Data Source
AI summary
The present invention provides a method for adiabatic cooling type crystallization of organic compound and an apparatus therefore, by which running cost and facility cost can be reduced.The method comprises carrying out adiabatic cooling and evaporation operation of a coolant in a crystallizer 20 for a mixture solution of a target organic compound containing the coolant; taking out crystal slurry produced by the operation from the crystallizer 20; pressurizing evaporated vapor to a pressure higher than the operation pressure in the crystallizer 20 by a compressor 30, introducing the vapor to an absorption condenser 10; cooling for condensation the mixture solution of organic compound and the evaporated vapor that has been pressurized while allowing them to contact each other in the absorption condenser 10; and introducing this absorption condensate to the crystallizer 20.