Process integration for natural gas liquid recovery
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Solution Overview
Problem
Current natural gas liquid recovery systems face inefficiencies in energy consumption and heat recovery due to the lack of effective process integration, leading to increased utility usage and operating costs in petroleum refineries.
Innovation Solution
The implementation of a natural gas liquid recovery system that includes a cold box with a plate-fin heat exchanger and a refrigeration system with a primary and secondary refrigerant loop, utilizing a mixture of hydrocarbons as refrigerants to enhance heat transfer and reduce energy consumption through optimized heat exchange processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional natural gas liquid recovery systems are used without process integration, then the system structure is simple, but energy consumption is high and heat recovery is inefficient
Solution Approach 1:
The patent combines the refrigeration system with the natural gas liquid recovery system into an integrated process. The refrigeration system's cold box is thermally coupled with the recovery system's heat exchangers, allowing heat transfer between process streams and refrigerant loops. This merging enables simultaneous cooling and NGL recovery functions, reducing overall energy consumption while managing system complexity through integrated design.
Solution Approach 2:
The integrated system performs multiple functions simultaneously: the refrigeration system provides cooling for the NGL recovery process while also enabling the separation and recovery of natural gas liquids. The heat exchangers serve dual purposes of heat transfer and mass separation, making the system multi-functional and more energy-efficient compared to separate standalone systems.
2Area of stationary object
If traditional heat exchange processes are used, then the equipment configuration is simple, but the heat transfer area required is large
Solution Approach 1:
The patent employs a nested heat exchanger configuration where the refrigerant tubes are positioned inside the shell of the heat exchanger, and process streams flow through the annular space. This nested arrangement maximizes heat transfer surface area within a compact volume, reducing the overall heat transfer area required while increasing equipment complexity through the nested structural design.
3Ease of manufacture
If process streams are not integrated, then the equipment and maintenance costs are high, but the process design is straightforward
Solution Approach 1:
The patent merges the refrigeration system with the NGL recovery system, allowing shared equipment and integrated operations. The cold box serves both refrigeration and heat recovery functions, reducing the total equipment required and lowering maintenance costs. This integration increases process design complexity but reduces overall equipment and maintenance expenses.
4Loss of energy
If utility streams are used for heating and cooling, then the process is simple to operate, but operating costs increase
Solution Approach 1:
The integrated system enables self-service heat transfer between process streams. Hot process streams provide heat to cool other process streams or refrigerant loops without requiring external utility streams. The system recovers and reuses heat internally, reducing utility consumption while maintaining operational simplicity through automated heat exchange processes.
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 solution reduces the total heat transfer area required, decreases power consumption in refrigerant compression, and integrates process streams to minimize equipment and maintenance costs, resulting in a more efficient and cost-effective natural gas liquid recovery process.
Implementation Method 1
The cold box is configured to transfer heat from hot fluids in the natural gas liquid recovery system to cold fluids in the natural gas liquid recovery system
Implementation Method 2
The primary refrigerant loop includes a primary refrigerant including a first mixture of hydrocarbons. The refrigeration system includes a secondary refrigerant loop. The secondary refrigerant loop includes a secondary refrigerant including i-butane.
Implementation Method 3
The refrigeration system includes a first subcooler configured to transfer heat between the primary refrigerant of the primary refrigerant loop and the secondary refrigerant of the secondary refrigerant loop
Implementation Method 4
The second subcooler is configured to transfer heat between the primary refrigerant and a vapor phase of the primary refrigerant
Data Source
AI summary
A natural gas liquid recovery system includes a cold box and a refrigeration system. The refrigeration system includes a primary refrigerant loop in fluid communication with the cold box. The primary refrigerant loop includes a primary refrigerant including a first mixture of hydrocarbons. The refrigeration system includes a secondary refrigerant loop. The secondary refrigerant loop includes a secondary refrigerant including i-butane. The refrigeration system includes a first subcooler configured to transfer heat between the primary refrigerant of the primary refrigerant loop and the secondary refrigerant of the secondary refrigerant loop. The refrigeration system includes a second subcooler downstream of the first subcooler. The second subcooler is configured to transfer heat between the primary refrigerant and a vapor phase of the primary refrigerant. The cold box is configured to receive the primary refrigerant from the second subcooler.