Cold Box Refrigeration Loop for Natural Gas Liquid Heat Recovery
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Solution Overview
Problem
Current natural gas liquid recovery systems face inefficiencies in energy consumption and heat recovery, particularly in petroleum refining processes, where existing heat integration techniques do not effectively utilize the thermal energy across multiple process streams.
Innovation Solution
The implementation of a natural gas liquid recovery system incorporating a cold box with a plate-fin heat exchanger and a primary refrigeration system using a mixed hydrocarbon refrigerant loop, which includes a throttling valve, separator, compressor, and subcoolers to efficiently transfer heat and condense vaporized refrigerant, thereby enhancing heat recovery and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat integration techniques are used in natural gas liquid recovery systems, then heat recovery is achieved, but energy consumption remains high and heat transfer area requirements are large
Solution Approach 1:
The patent utilizes phase transitions of the primary refrigerant (evaporation and condensation) to transfer heat between process streams. The refrigerant evaporates in the cold box to absorb heat from cold streams, then condenses in the condenser to release heat to hot streams, creating an efficient heat recovery cycle that reduces overall energy consumption while maximizing heat recovery efficiency
Solution Approach 2:
The primary refrigerant acts as an intermediary substance that facilitates heat transfer between multiple process streams. Instead of direct heat exchange between all streams, the refrigerant mediates the thermal energy transfer through its phase change cycle, enabling efficient heat recovery while reducing the required heat transfer area and energy consumption
2Temperature
If conventional refrigeration systems are used, then refrigeration is provided, but power consumption in refrigerant compression is high
Solution Approach 1:
The patent changes the physical parameters of the refrigeration system by using a mixed hydrocarbon refrigerant composition and operating at optimized pressure-temperature conditions. The compressor is designed to operate at specific pressure ratios that minimize power consumption while achieving the required refrigeration temperatures, and the system maintains these optimized parameters throughout operation
3Loss of energy
If large heat transfer area is used, then heat exchange efficiency is improved, but system complexity and cost increase
Solution Approach 1:
The patent employs phase transitions of the refrigerant to achieve efficient heat exchange with reduced surface area. The latent heat absorbed during evaporation and released during condensation allows for compact heat exchanger design, maintaining high heat exchange efficiency while reducing system complexity and cost compared to systems requiring large heat transfer areas without phase change
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 configuration reduces the total heat transfer area required, decreases power consumption in refrigerant compression, and integrates heat exchange across various process streams, leading to lower operating costs and maintenance needs while improving the overall efficiency of the 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 cold box includes a plate-fin heat exchanger including compartments
Implementation Method 3
The throttling valve is configured to reduce pressure of the primary refrigerant
Implementation Method 4
The refrigerant separator is configured to separate the primary refrigerant into a primary refrigerant liquid phase and a primary vapor phase
Implementation Method 5
The compressor is configured to increase pressure of the stream of vaporized primary refrigerant
Implementation Method 6
The one or more coolers are cooperatively configured to fully condense the stream of vaporized primary refrigerant from the compressor
Implementation Method 7
The first subcooler is configured to receive, at the first side of the first subcooler, the primary refrigerant vapor phase from the refrigerant separator and configured to receive, at the second side of the first subcooler, the primary refrigerant from the one or more coolers
Data Source
AI summary
This specification relates to operating industrial facilities, for example, crude oil refining facilities or other industrial facilities that include operating plants that process natural gas or recover natural gas liquids.