Two-Stage Quench Tower System for Pyrolysis Product Cooling

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Solution Overview

Problem

The existing thermal decomposition processes for naphtha face challenges in maintaining process stability and separation efficiency of the quench tower due to increased differential pressure from the outlet of the decomposition furnace to the inlet of the compressor, which limits the output of the thermal decomposition product.

Innovation Solution

A method involving the supply of discharge streams from multiple decomposition furnaces to a secondary quench tower, allowing for efficient cooling and separation of thermal decomposition products within the limited capacity of the quench tower, thereby managing the differential pressure and maintaining the pressure at the outlet of the decomposition furnace at a desired level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the decomposition furnace is added to increase thermal decomposition product capacity, then the output of thermal decomposition product is increased, but the differential pressure from outlet of decomposition furnace to inlet of compressor increases

Engineering Contradiction:
Improveoutput of thermal decomposition productVSAvoiddifferential pressure from outlet of decomposition furnace to inlet of compressor
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

The quenching process is divided into two stages: a first quench tower handles the initial quenching of thermal decomposition products, while a second quench tower performs further quenching. This segmentation allows the system to handle increased product capacity from multiple decomposition furnaces without excessively increasing differential pressure, as the quenching load is distributed across two towers rather than one.

Inventive Principle:
Principle #1Segmentation

2Productivity

If the pressure at outlet of decomposition furnace is increased to transport more stream to compressor, then the compressor output is increased, but the selectivity of thermal decomposition reaction is decreased

Engineering Contradiction:
Improvecompressor outputVSAvoidselectivity of thermal decomposition reaction
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The system changes the pressure parameter management by using two quench towers to maintain more stable pressure conditions. The first quench tower operates at a pressure that preserves reaction selectivity, while the second quench tower further processes the stream. This allows the compressor inlet pressure to be increased for higher output without requiring excessive increases in decomposition furnace outlet pressure that would harm reaction selectivity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If multiple decomposition furnaces are added to increase product capacity, then the thermal decomposition product supply is increased, but the separation efficiency of quench tower is lowered

Engineering Contradiction:
Improvethermal decomposition product supplyVSAvoidseparation efficiency of quench tower
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The quenching and separation process is segmented into two towers: the first quench tower performs initial quenching and separation, while the second quench tower performs further quenching and separation. This segmentation allows each tower to handle a portion of the thermal decomposition products from multiple furnaces, maintaining separation efficiency that would be difficult to achieve in a single overloaded tower.

Inventive Principle:
Principle #1Segmentation

4Productivity

If the pressure at inlet of compressor is increased to increase output, then the mass of stream transported is increased, but the pressure at outlet of decomposition furnace must be increased which lowers selectivity

Engineering Contradiction:
Improvecompressor outputVSAvoidselectivity of thermal decomposition reaction
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The two-quench-tower system acts as an intermediary between the decomposition furnaces and the compressor. By introducing these intermediate quenching stages, the system can increase compressor inlet pressure for higher output without directly increasing decomposition furnace outlet pressure, thereby protecting reaction selectivity. The quench towers mediate the pressure and flow conditions between production and compression.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach improves process stability and separation efficiency of the quench tower, allowing for increased output of the thermal decomposition product while maintaining the pressure at the outlet of the decomposition furnace within a certain level, even with increased pressure at the compressor inlet.

Implementation Method 1

a method of quenching a pyrolysis product includes: quenching a discharge stream from a liquid decomposition furnace in a first quench tower

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

quenching a discharge stream from a liquid decomposition furnace in a first quench tower; and quenching an upper discharge stream from the first quench tower and a discharge stream from a gas decomposition furnace in a second quench tower

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3663381B1Method for cooling pyrolysis product
Publication Date: 2021.05.12 LG CHEM LTD
  • EP3663381B1 patent drawingFigure 1~2

AI summary

Provided is a method for quenching a pyrolysis product, and more particularly, a method for quenching a pyrolysis product, including: supplying a discharge stream from a liquid decomposition furnace to a first quench tower; supplying an upper discharge stream from the first quench tower to a second quench tower; supplying a discharge stream from a first gas decomposition furnace to the second quench tower; and supplying a discharge stream from a second gas decomposition furnace to the second quench tower.