Heat Pump Integration on Dividing Wall Column Bottom Section
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Solution Overview
Problem
Current de-isopentanizer (DIP) and de-isobutanizer (DIB) column systems in Natural Gas Liquid (NGL) fractionation plants face challenges in achieving energy efficiency and low operational costs while maintaining high separation efficiency.
Innovation Solution
A dividing wall column system with a bottom dividing wall and a heat pump that compresses overhead product vapor to heat a second reboiler, reducing energy consumption and optimizing heat integration by using vapor to strip hydrocarbons, thereby enhancing separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional multi-column configuration is used for NGL fractionation, then separation of hydrocarbon components can be achieved, but energy consumption and operational costs increase due to multiple reboilers and lack of heat integration
Solution Approach 1:
The patent combines multiple separation functions into a single dividing wall column (DWC) unit. The DWC integrates the functionality of multiple columns by using internal dividing walls to create separate stripping sections for different hydrocarbon components (C4, C5, etc.) within one column structure, eliminating the need for multiple separate columns and their associated reboilers, thereby reducing energy consumption while maintaining separation efficiency
Solution Approach 2:
The patent implements heat integration by changing the temperature parameters of process streams. The overhead vapor from the DWC is routed to a heat exchanger where it provides heat to reboiler feed streams, transforming the temperature profile of these streams and recovering energy that would otherwise be lost, thus reducing the energy required by external heating utilities
2Manufacturing precision
If multiple reboilers are used in each column, then complete separation of hydrocarbon fractions can be achieved, but operational costs and energy consumption increase
Solution Approach 1:
The patent merges multiple reboiling functions into a single reboiler unit located at the bottom of the dividing wall column. This single reboiler provides the necessary vapor for stripping multiple hydrocarbon components (C4, C5, etc.) simultaneously through the divided stripping sections, eliminating the need for multiple separate reboilers and reducing operational costs while maintaining complete separation efficiency
Solution Approach 2:
The patent implements a self-service heat integration scheme where the overhead vapor from the DWC serves as the heating medium for the reboiler. The vapor condenses in the heat exchanger, providing the heat necessary for the reboiler to vaporize the bottom feed stream, thereby reducing or eliminating the need for external heating utilities and reducing operational costs
3Reliability
If overhead vapor is condensed using conventional cooling water systems, then product recovery is achieved, but cooling water requirements and emissions increase
Solution Approach 1:
The patent implements a self-service heat integration scheme where the overhead vapor from the dividing wall column serves as the heating medium for the reboiler. The vapor condenses in the heat exchanger, providing the heat necessary for the reboiler to vaporize the bottom feed stream, thereby reducing or eliminating the need for external heating utilities and reducing operational costs
Solution Approach 2:
The patent converts the harmful waste heat in the overhead vapor stream into a beneficial heating resource. Instead of discarding the hot overhead vapor to cooling water systems (which generates emissions and requires large amounts of cooling water), the system routes this vapor to heat exchangers where it provides process heating for reboiler feeds, transforming a harmful waste stream into a useful energy resource and reducing emissions and cooling water requirements
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
The system achieves significant energy savings, reduced cooling water and heating medium requirements, lower operational costs, and high separation efficiency, while maintaining a smaller footprint and lower emissions.
Implementation Method 1
a first portion of the overhead product from the dividing wall column is compressed in the heat pump
Implementation Method 2
the heat pump is also in fluid communication with the second reboiler so that a first portion of the overhead product (or light product respectively) of the dividing wall column is compressed in the heat pump and then fed to the second reboiler in order to heat at least a portion of the bottom product
Implementation Method 3
the vapor generated in the first reboiler is used to strip the teed on the first side of the bottom section defined by the dividing wall of C4-hydrocarbon material, which produces a C5+-hydrocarbon product on that side of the bottom section of the dividing wall column
Data Source
AI summary
A dividing wall column system is provided. The dividing wall column system comprises a dividing wall column, a first reboiler, a second reboiler, and a heat pump. The dividing wall column includes a dividing wall positioned in a bottom section of the dividing wall column to divide the bottom section of the dividing wall column into a first side and a second side. The first reboiler is outside of the dividing wall column and in fluid communication with the first side of the bottom section of the dividing wall column. The second reboiler is outside of the dividing wall column and in fluid communication with the second side of the bottom section of the dividing wall column. The heat pump is in fluid communication with the dividing wall column and the second reboiler and configured to compress a first portion of an overhead product from the dividing wall column.