Integrated Refrigerant Precooling in Hydrocarbon Liquefaction
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Solution Overview
Problem
Current methods for liquefying hydrocarbon streams, such as natural gas, are inefficient and costly, particularly in terms of capital and running expenses, and often require extensive space and complex equipment setups.
Innovation Solution
A method involving a two-stage cooling process using shell and tube heat exchangers with a single component refrigerant like propane in the first stage and a mixed refrigerant in the second stage, where the second refrigerant is pre-cooled by passing through the first stage's heat exchangers, reducing the need for separate cooling equipment and simplifying the refrigerant compression system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate heat exchangers are used for first refrigerant and second refrigerant cooling, then cooling effectiveness is improved, but device complexity and capital costs increase
Solution Approach 1:
The patent combines the cooling functions for the first refrigerant and second refrigerant into a single integrated heat exchanger unit. The first refrigerant cools the hydrocarbon stream while simultaneously cooling the second refrigerant in the same heat exchanger, eliminating the need for separate cooling equipment and reducing overall system complexity.
Solution Approach 2:
The heat exchanger is designed to perform multiple functions: cooling the hydrocarbon stream with the first refrigerant, and simultaneously cooling the second refrigerant. This multi-functional design reduces the total number of equipment pieces required while maintaining effective cooling for both refrigerants.
2Power
If multiple separate refrigerant circuits are used, then refrigeration capacity is improved, but running costs and capital expenses increase
Solution Approach 1:
The patent merges the refrigerant circuits so that the second refrigerant circuit utilizes the cooling capacity of the first refrigerant circuit. The second refrigerant is cooled by the first refrigerant in the same heat exchanger, reducing the total refrigeration capacity required from separate independent systems and thereby lowering both capital and operating costs.
Solution Approach 2:
The first refrigerant acts as an intermediary cooling medium for the second refrigerant. Instead of requiring the second refrigerant to be cooled by an independent system, it uses the first refrigerant as a mediator, transferring cooling energy efficiently and reducing overall system costs.
3Reliability
If extensive cooling equipment is used for second refrigerant, then cooling performance is improved, but space requirements increase
Solution Approach 1:
The patent combines the cooling functions for both refrigerants into a single heat exchanger unit, eliminating the need for separate cooling equipment for the second refrigerant. This integration significantly reduces the space required for the liquefaction plant while maintaining effective cooling performance for both refrigerants.
Solution Approach 2:
The second refrigerant cooling function is nested within the first refrigerant cooling system. The heat exchanger is designed so that the second refrigerant cooling channels are integrated within the same structure that cools the hydrocarbon stream, creating a compact nested arrangement that minimizes space usage.
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 capital and operating costs, minimizes space requirements, and enhances efficiency by combining cooling duties across stages, making it suitable for compact liquefaction plants with reduced equipment complexity.
Implementation Method 1
passing the feed stream through a first cooling stage having at least two heat exchangers, and against a first refrigerant in a first single component refrigeration circuit
Implementation Method 2
passing the second refrigerant through one or more of the heat exchangers of the first cooling stage; wherein the heat exchangers of the first cooling stage are shell and tube heat exchangers
Implementation Method 3
passing the cooled hydrocarbon stream through a second cooling stage against a second refrigerant in a second refrigerant circuit, to provide a liquefied hydrocarbon stream
Data Source
AI summary
Method of liquefying a hydrocarbon stream from a feed stream including (a) passing the feed stream through a first cooling stage having at least two heat exchangers and against a component refrigerant in a first refrigerant circuit, to provide a cooled hydrocarbon stream; (b) passing the cooled hydrocarbon stream through a second cooling stage against a second refrigerant in a second refrigerant circuit, to provide a liquefied hydrocarbon stream; (c) passing the second refrigerant through one of the heat exchangers of the first cooling stage. The heat exchangers of the first cooling stage are shell and tube heat exchangers having two or more tube circuits. The first refrigerant circuit includes a refrigerant compressor and the second refrigerant circuit includes a refrigerant compressor. The refrigerant compressor of the first refrigerant circuit and the refrigerant compressor of the second refrigerant circuit are interconnected and are arranged to be driven by a common driver.