Quench Water Settlers Tar Separation Steam Cracker
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Solution Overview
Problem
Fouling in steam cracker quench systems, particularly exacerbated by high propane content in feedstock, leads to poor energy efficiency, reduced production rates, and potential plant shutdowns due to plugging and fouling of heat exchangers.
Innovation Solution
Implementing a quench water loop design with extended residence time in quench oil/water settlers to enhance oil/water separation, thereby minimizing tar-like fouling material entrainment and reducing fouling in the quench water system by using multiple settlers with specific baffle configurations and residence times to separate tar from water effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If quench water is circulated through heat exchangers to cool the system, then energy efficiency is improved, but fouling of heat exchanger tubes occurs due to tar deposits
Solution Approach 1:
The patent applies preliminary action by implementing a quench oil/water settler that separates tar from quench water before the water is circulated to heat exchangers. This preliminary separation prevents tar deposits from forming in the heat exchanger tubes, allowing continuous operation without fouling while maintaining energy efficiency.
Solution Approach 2:
The patent extracts the harmful tar component from the quench water stream using a quench oil/water settler. The settler separates tar from water, and the extracted tar is removed from the system while the cleaned water is recirculated to heat exchangers, preventing fouling while maintaining cooling efficiency.
2Object-generated harmful factors
If residence time in quench settlers is extended to improve oil/water separation, then tar entrainment is reduced, but system complexity and equipment size increase
Solution Approach 1:
The patent segments the quench settling process into multiple separate settler units rather than using a single large settler. This segmentation allows for more efficient oil/water separation in each unit while managing overall system complexity through modular design. The multiple settlers provide extended effective residence time without requiring one excessively large complex vessel.
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 solution effectively reduces fouling in steam cracker quench systems by improving oil/water separation, minimizing tar entrainment, and maintaining system efficiency, preventing plant shutdowns and ensuring continuous operation.
Implementation Method 1
settle the bottom stream containing pyrolysis gasoline in two or more quench water settlers in parallel to produce a settler hydrocarbon stream, a settler bottom quench water stream, and a settler water stream
Implementation Method 2
The superheated cracked gas is flowed into the bottom of the quench water tower and, at the same time, water is sprayed into the top of the quench water tower. As the water in the quench water tower falls, it makes contact with the upwardly flowing superheated cracked gas and, in that way, cools the superheated cracked gas and dilution steam.
Implementation Method 3
Because of the direct contact between the superheated cracked gas in the quench water tower and the condensation of the dilution steam, the water flowing from the quench water tower is mixed with condensed hydrocarbons
Data Source
AI summary
Methods that reduce fouling of equipment in a quench water recycling loop of a steam cracker quench system by separating tar from water in the quench water recycling loop. The methods may include settling a bottom stream comprising pyrolysis gasoline, from a quench tower, in at least two quench water settlers in parallel, each of the quench water settlers producing a settler hydrocarbon stream and a settler bottom quench water stream. The methods may also include mixing a bottom stream comprising pyrolysis gasoline, from a quench tower, with quench tower effluent water to form a combined stream. The method may further include settling the combined stream in at least two quench water settlers in parallel to produce settler hydrocarbon streams, settler bottom quench water streams, and settler process water streams.