Integrated Cold Box Heat Exchanger 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, particularly in the heating and cooling processes involved in petroleum refining.
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 efficiently transfer heat and condense feed gases, thereby enhancing energy efficiency and reducing utility usage.
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 multiple heat exchange operations into a single integrated cold box system with plate-fin heat exchangers. The cold box integrates refrigeration cycles, heat recovery, and natural gas liquid separation functions that were previously performed by separate units, thereby reducing energy consumption while managing system complexity through functional integration
Solution Approach 2:
The cold box system performs multiple functions simultaneously: it provides refrigeration for gas cooling, recovers heat from process streams, separates natural gas liquids, and pre-cools feed gas. This multi-functionality reduces the need for separate dedicated equipment, improving energy efficiency without proportionally increasing system complexity
2Loss of energy
If process integration with heat exchange is implemented, then heat recovery is improved and energy efficiency increases, but device complexity increases
Solution Approach 1:
Multiple heat exchangers are merged into integrated plate-fin heat exchanger assemblies within the cold box. These consolidated units recover heat from various process streams (refrigerant condensers, gas outlets, liquid outlets) and transfer it to feed gas and other cold streams, maximizing heat recovery while reducing the number of separate heat exchange devices
Solution Approach 2:
The heat exchange network operates continuously to recover heat from all process streams. The integrated cold box system maintains continuous heat transfer between hot and cold streams throughout operation, ensuring that useful heat recovery action is ongoing without interruption, thereby reducing overall energy loss
3Ease of operation
If utility streams are used for heating and cooling, then process operations are maintained, but operating costs increase
Solution Approach 1:
The process system serves itself by internally recovering and redistributing heat from process streams. The cold box system uses heat from refrigerant condensation, gas outlet streams, and liquid outlet streams to cool feed gas and other process streams, reducing or eliminating the need for external utility steam and cooling water, thereby reducing operating costs while maintaining process operations
Solution Approach 2:
Heat that would otherwise be discarded from process streams (refrigerant condenser heat, hot gas outlet heat, hot liquid outlet heat) is recovered and reused to cool feed gas and other cold streams. This recovery and reuse of previously wasted thermal energy reduces utility consumption while keeping the process running efficiently
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 energy consumption, decreases operating costs, and improves heat recovery by effectively integrating heat exchange across various process streams, leading to 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 chill down train can be configured to condense at least a portion of the feed gas in at least one compartment of the cold box
Implementation Method 3
The separator can be configured to separate the feed gas into a liquid phase and a refined gas phase
Implementation Method 4
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
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.