Two-Stage Contact Cooler for Olefin Cracking Effluent
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Solution Overview
Problem
Existing olefin cracking processes face inefficiencies in cooling olefin cracking reactor effluent streams, leading to reduced compression capacity, increased energy expenditure, and decreased yield of light olefins due to fouling and pressure drops in heat exchange units.
Innovation Solution
A process and system involving a contact cooler with multiple quench liquids and heat exchangers to efficiently cool olefin cracking reactor effluent streams, minimizing pressure drop and returning cooled streams as quench liquids to maintain efficiency and yield, utilizing a contact cooler with first and second contact zones and heat exchangers to manage temperature and pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage heat exchanger is used to cool olefin cracking reactor effluent stream, then the cooling process is simple, but fouling and pressure drops increase leading to reduced compression capacity and decreased yield of light olefins
Solution Approach 1:
The cooling process is divided into two distinct stages: a first contact cooler that performs initial cooling and separation, followed by a second heat exchanger that performs final cooling. This segmentation allows each stage to be optimized for its specific function, reducing overall fouling and pressure drop while maintaining high yield of light olefins
2Use of energy by moving object
If elevated temperature cooling is used to maintain compression capacity, then energy expenditure decreases, but fouling increases leading to pressure drops and reduced yield
Solution Approach 1:
The cooling temperature profile is segmented into two zones: the first contact cooler operates at higher temperatures to minimize fouling while removing initial heat, and the second heat exchanger operates at lower temperatures for final cooling. This segmented approach allows energy-efficient cooling while controlling fouling at each stage
Solution Approach 2:
The first contact cooler acts as an intermediary device between the high-temperature reactor effluent and the second heat exchanger. It performs preliminary cooling and separation, reducing the temperature and fouling potential before the stream enters the second heat exchanger, thereby enabling more efficient overall heat recovery
3Loss of energy
If aggressive cooling is applied to maximize compression capacity, then energy expenditure is reduced, but pressure drops increase due to fouling decreasing yield
Solution Approach 1:
The cooling system is segmented into two stages where the first contact cooler handles the bulk of heat removal at temperatures that minimize fouling, and the second heat exchanger completes the cooling. This segmentation reduces cumulative pressure drops while maximizing energy recovery and compression capacity
4Productivity
If a two stage contact cooler is used to reduce fouling and pressure drops, then yield of light olefins is enhanced, but device complexity increases
Solution Approach 1:
The first contact cooler combines multiple functions into a single device: initial heat exchange, vapor-liquid separation, and preparation for the second cooling stage. This merging of functions reduces overall system complexity while maintaining the benefits of two-stage cooling for enhanced yield
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 proposed solution effectively cools olefin cracking reactor effluent streams, reducing fouling and pressure drops, thereby enhancing the yield of light olefins and minimizing energy consumption, while maintaining efficient compression and separation processes.
Implementation Method 1
the olefin cracking reactor effluent stream is contacted with a first quench liquid in a first contact zone to produce a first bottoms stream and an intermediate vapor stream. The intermediate vapor stream is contacted with a second quench liquid in a second contact zone in the contact cooler to produce a second bottoms stream and a cooled vapor stream
Implementation Method 2
The first heat exchanger that removes heat from the first bottoms stream by indirect heat exchange with a first cooling liquid. The second heat exchanger that removes heat from the second bottoms stream by indirect heat exchange with a second cooling liquid
Data Source
AI summary
Systems and methods are provided herein for cooling an olefin cracking reactor effluent stream. One provided method includes reacting a hydrocarbon feedstock including C4+ olefins in an olefin cracking reactor to produce an olefin cracking reactor effluent stream, providing the olefin cracking reactor effluent stream to an inlet of a contact cooler, contacting the olefin cracking reactor effluent stream with a first quench liquid in a first contact zone in the contact cooler to produce a first bottoms stream and an intermediate vapor stream, contacting the intermediate vapor stream with a second quench liquid in a second contact zone in the contact cooler to produce a second bottoms stream and a cooled vapor stream, and removing the cooled vapor stream from an outlet of the contact cooler. The method can also include cooling the first bottoms stream to provide a cooled first bottoms stream, and cooling the second bottoms stream to provide a cooled second bottoms stream.