Ejector Recycle Gas Cooling for Faster Unit Operation Cooldown
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Solution Overview
Problem
Existing methods for cooling equipment in elevated temperature unit operations, such as those in chemical and petrochemical processing, face limitations in cooldown efficiency and cost due to the need for specialized equipment like recycle compressors, leading to inefficiencies in coolant gas usage and extended maintenance times.
Innovation Solution
A method utilizing a non-mechanical pump to combine vaporized cryogenic fluid with effluent gas from the unit operation, creating a cooling stream for direct contact heat exchange, which adjusts temperature and flow rates to achieve efficient cooldown without requiring a recycle compressor, using a jet compressor to mix and circulate gases effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a recycle compressor is used to recirculate effluent gas for cooling, then the cooldown rate is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical recycle compressor with a non-mechanical ejector system that uses fluid dynamics (Venturi effect) to recirculate effluent gas. The ejector uses a motive fluid (cold inert gas or process fluid) to create a vacuum that draws effluent gas through the heat exchanger, eliminating the need for mechanical compression while maintaining recirculation capability for effective cooldown
Solution Approach 2:
The invention employs pneumatic principles by using gas flow and pressure differentials to drive the cooling process. The ejector utilizes the Venturi effect where high-velocity motive fluid creates a low-pressure zone that entrains and recirculates effluent gas through the heat exchanger, replacing mechanical compression with fluid dynamic control
2Productivity
If coolant gas is injected to accelerate cooldown, then the cooldown rate is improved, but the quantity of coolant gas consumption increases
Solution Approach 1:
The patent recovers and recirculates effluent gas that would otherwise be discarded through the flare system. By routing effluent gas through the heat exchanger multiple times via the ejector recirculation system, the cooling capacity is multiplied while reducing the net consumption of fresh coolant gas. The system recovers thermal energy from the effluent stream and uses it to pre-cool incoming coolant gas
Solution Approach 2:
The ejector recirculation system maintains continuous circulation of effluent gas through the heat exchanger, ensuring sustained heat transfer throughout the cooldown process. This continuous recirculation maximizes the utilization of available coolant gas by repeatedly passing it through the heat exchanger, thereby reducing overall consumption while maintaining high cooldown rates
3Device complexity
If a once-through cooling process is used, then the device complexity is reduced, but the coolant gas consumption increases and flow limitations occur
Solution Approach 1:
The patent merges the cooling function with the existing effluent gas handling system by integrating the ejector recirculation into the process flow. The effluent gas stream, which already exists in the system, is combined with the cooling function through the heat exchanger and ejector, eliminating the need for separate dedicated cooling equipment while reducing coolant consumption through recirculation
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 reduces coolant gas consumption, enhances cooldown rates, and shortens maintenance times by enabling efficient gas recirculation and temperature control, making it more economical and environmentally friendly.
Implementation Method 1
A method utilizing a non-mechanical pump to combine vaporized cryogenic fluid with effluent gas from the unit operation, creating a cooling stream for direct contact heat exchange
Implementation Method 2
passing the cooling stream through the unit operation to cool it using direct contact heat exchange
Data Source
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AI summary
The present invention relates to a method of preparing a gas coolant for the direct cooling of a unit operation under a fixed heat load from its normal operating temperature (e.g., 300°F and above) to a lower temperature (e.g., below 100°F) in order to allow for maintenance or other non-routine work to be carried out in said unit operation.