Cold Box Heat Integration for Natural Gas Liquid Recovery
Find Innovative SolutionsGenerate Solutions
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 potential for reducing utility usage and operating costs.
Innovation Solution
The implementation of a natural gas liquid recovery system incorporating a cold box with a plate-fin heat exchanger and a refrigeration system using a primary refrigerant mixture of 61% to 69% C3 hydrocarbons and 31% to 39% C4 hydrocarbons, which includes low and high-pressure refrigerant separators to optimize heat transfer and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional heat integration techniques are used in natural gas liquid recovery systems, then the system can operate with standard equipment arrangements, 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 by integrating the cold box heat exchanger into both processes. The refrigeration system's cold box serves dual purposes: providing refrigeration for natural gas processing while simultaneously recovering heat from process streams. This merging eliminates the need for separate heat recovery equipment and enables efficient energy utilization across both systems.
Solution Approach 2:
The patent utilizes phase changes of the refrigerant (evaporation and condensation) to transfer heat between process streams. The refrigerant evaporates at low temperatures to cool process gases, then condenses at higher temperatures to transfer heat to other streams. This parameter change approach enables efficient heat recovery across different temperature levels, improving overall energy utilization.
2Use of energy by stationary object
If a refrigeration system with separate heat exchangers is used, then heat transfer can be achieved, but the total heat transfer area required increases and equipment complexity increases
Solution Approach 1:
The patent merges multiple heat transfer functions into a single cold box unit. Instead of using separate heat exchangers for refrigeration and heat recovery, the cold box performs both functions simultaneously by exchanging heat between refrigerant streams and process streams within the same equipment structure, thereby reducing equipment complexity while maintaining heat transfer efficiency.
Solution Approach 2:
The cold box heat exchanger is designed to serve multiple functions: it provides refrigeration cooling for natural gas processing, recovers heat from hot process streams, and condenses refrigerant vapor. This multi-functional design eliminates the need for dedicated equipment for each function, reducing overall system complexity while achieving efficient heat transfer.
3Loss of energy
If traditional heat exchanger arrangements are used, then the system can be simpler in configuration, but the heat transfer area required increases leading to higher capital costs
Solution Approach 1:
The patent exploits the phase change parameters of the refrigerant (liquid to vapor during evaporation, vapor to liquid during condensation) to maximize heat transfer coefficients. These phase transitions occur at constant temperature but involve large latent heat transfers, enabling significant heat recovery in compact equipment with reduced surface area compared to conventional sensible heat exchange arrangements.
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 enhances energy efficiency by effectively transferring heat between hot and cold fluids, reducing the total heat transfer area required and lowering power consumption in the refrigeration system, thereby decreasing operating costs and maintenance needs.
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 LP refrigerant separator is configured to separate phases of the second portion of the primary refrigerant into a LP primary refrigerant liquid phase and a LP primary refrigerant vapor phase
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.