Cracking Furnace Thermal Shielding for Mechanical Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional steam cracking furnaces experience suboptimal heat distribution and mechanical stability issues due to staggered coil arrangements, leading to inefficient cracking conditions and potential tube rupture from thermal stresses and creep.
Innovation Solution
Designing the cracking furnace with outlet sections more thermally shielded than inlet sections, and arranging burners and coils in a configuration where inlet sections act as thermal shields, reducing thermal duty at outlet sections and enhancing mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If staggered coil arrangements are used in conventional steam cracking furnaces, then heat distribution is achieved, but mechanical stability deteriorates due to thermal stresses and creep leading to tube rupture
Solution Approach 1:
The patent applies asymmetry by positioning outlet sections of cracking coils in a dedicated lane between burner lanes, while inlet sections are positioned in lanes between burners and outlet sections. This asymmetric arrangement creates thermal shielding where inlet sections protect outlet sections from direct radiant heat, reducing thermal stresses and creep on outlet sections while maintaining effective heat distribution to inlet sections.
2Reliability
If outlet sections are thermally shielded by inlet sections, then mechanical stability improves, but heat input efficiency to outlet sections reduces
Solution Approach 1:
The patent applies local quality by providing different thermal environments to different sections of the cracking coils. Inlet sections are positioned to receive direct radiant heat from burners for efficient heating, while outlet sections are positioned behind thermal shields (inlet sections) to receive reduced heat input. This localized differentiation allows each section to operate under optimal thermal conditions for its specific function.
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 improves heat input efficiency, reduces residence time, increases mechanical stability, and enhances ethylene production capacity while minimizing coke formation and operator intervention, allowing for longer furnace operation and reduced maintenance intervals.
Implementation Method 1
the outlet sections (7) are positioned in between a first lane of burners (5) and a second lane of burners (5), wherein the inlet sections (6) are positioned in between the outlet sections (7) and the burners (5), thereby partly thermally shielding the outlet sections (7)
Implementation Method 2
A number of reactor tubes (known as cracking tubes or cracking coils) through which the feed can pass, are disposed through the firebox. The vapour feed in the tubes is heated to such a high temperature that rapid decomposition of molecules occurs
Implementation Method 3
The cracking is carried out at much higher severity than applied in the moderate cracking of liquid hydrocarbon oils to improve fluid quality. The vapour feed in the tubes is heated to such a high temperature that rapid decomposition of molecules occurs, which yields desired light olefins such as ethylene and propylene
Data Source
AI summary
A cracking furnace having a firebox provided with cracking coils is described. The cracking coils have at least one inlet, at least one inlet section, at least one outlet and at least one outlet section, and burners, and the parts of the coils are shielded. A process for cracking hydrocarbon feeds, and making use of a furnace with the thermal shielding are also described.