Coke-Integrated Feed Preheating for Lower-Emission Steam Cracking
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Solution Overview
Problem
Conventional steam cracking processes face issues with CO2 emissions, petcoke disposal, and inefficient utilization of convection section energy, leading to SCOPE-II and SCOPE-III CO2 emissions and petcoke disposal challenges.
Innovation Solution
A preheating process module integrated with a coke handling system uses petcoke combustion to indirectly heat hydrocarbon feedstock through a circulating stream of heat carrier particles, capturing CO2 and generating high-pressure steam, thereby reducing emissions and utilizing convection section energy for additional steam generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional steam cracking uses hot flue gas from radiant section to preheat hydrocarbon feedstock in convection section, then preheating function is achieved, but energy consumption is high and convection section efficiency is reduced
Solution Approach 1:
The patent introduces a heat carrier particle system as an intermediary between the combustion process and the hydrocarbon feedstock. Petcoke is combusted to heat heat carrier particles (such as ceramic balls or metal oxides), which then circulate through heat exchangers to preheat the feedstock. This intermediary system allows efficient heat transfer while separating the combustion zone from the preheating zone, thereby reducing energy losses in the convection section.
Solution Approach 2:
The patent replaces the conventional thermal convection system (hot flue gas flow) with a particulate heat carrier system. Instead of relying on bulk gas movement for heat transfer, the system uses solid particles that can be heated to high temperatures and circulated through controlled pathways, enabling more efficient and controllable heat transfer to the feedstock.
2Power
If petcoke is combusted in conventional locations, then energy for heating is generated, but CO2 emissions increase and petcoke disposal issues arise
Solution Approach 1:
The patent converts the harmful effect of petcoke (a disposal problem and CO2 source) into a beneficial energy source. By combusting petcoke in a controlled fluidized bed combustor to generate heat for the heat carrier particles, the system transforms a waste product into a valuable energy source, simultaneously solving the petcoke disposal issue and providing process heat while enabling CO2 capture.
Solution Approach 2:
The patent implements a system where petcoke is combusted and the resulting CO2 is captured and separated from the flue gas. The heat carrier particles are recovered and circulated back to the combustor, while the CO2 is recovered for potential utilization or storage, preventing its release into the atmosphere.
3Productivity
If preheating temperature is increased to improve cracking efficiency, then productivity increases, but control over thermal cracking patterns becomes difficult
Solution Approach 1:
The patent implements a dynamic heat carrier particle circulation system where parameters such as particle circulation rate, residence time in heat exchangers, and combustion intensity can be independently adjusted. This dynamic control allows precise regulation of feedstock preheating temperature and residence time, enabling optimization of cracking patterns and product distribution while maintaining high productivity.
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 SCOPE-II and SCOPE-III CO2 emissions, addresses petcoke disposal, and generates additional high-pressure steam for utility, enhancing energy efficiency and reducing feedstock contamination.
Implementation Method 1
preheating the hydrocarbon feedstock using heat carrier particles in a continuous circulation process
Implementation Method 2
circulating stream of heat carrier particles
Implementation Method 3
combustion of petcoke indirectly through a circulating stream of heat carrier particles
Data Source
AI summary
A process for steam cracking a hydrocarbon feedstock in a hydrocarbon cracking furnace is disclosed. The hydrocarbon feedstock is preheated in a preheating process module that is integrated with a coke handling system for supply of coke required for combustion. The coke is combusted in presence of oxygen containing gas to heat the heat carrier particles. The heat carrier particles contact the hydrocarbon feedstock to generate preheated hydrocarbon vapors. The flue gas generated by combustion of the coke is contacted with steam in an upper section of the heat source vessel to form dilution steam which mixes with the preheated hydrocarbon vapors to create a mixed stream The mixed stream is fed to the hydrocarbon cracking furnace for thermal cracking.