Steam Cracking Feed Preheating Through Steam Heat Exchange
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Solution Overview
Problem
Conventional steam cracking processes face challenges in efficiently preheating and evaporating hydrocarbon feedstocks using electric heaters, particularly for hydrocarbons with wide boiling ranges and high fouling potential, leading to equipment fouling and heater failure.
Innovation Solution
A method and system that utilizes steam as a heat medium to preheat and superheat hydrocarbon feedstocks, with at least 90% of the heat for preheating provided by steam, minimizing direct electrical heating to reduce fouling risks, using a two-stage preheating process with different steam pressures and temperatures in feed preheaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electric heaters are used to preheat and evaporate hydrocarbon feedstocks, then the heating efficiency is improved, but equipment fouling increases and heater failure occurs
Solution Approach 1:
The patent introduces steam as an intermediary heat transfer medium between the electric heater and the hydrocarbon feedstock. The electric heater heats the steam, and the steam then preheats and evaporates the hydrocarbon feedstock in a separate heat exchange process. This intermediary approach prevents direct contact between the heating element and the hydrocarbon, eliminating fouling on the heater surface while maintaining efficient heat transfer through the steam's high thermal conductivity and phase change capabilities.
2Loss of energy
If conventional fuels are used for heating in steam cracking furnaces, then the heat balance is maintained, but carbon dioxide emissions increase
Solution Approach 1:
The patent replaces the conventional chemical combustion system (burning fossil fuels) with an electrical heating system. Electric heaters generate heat through resistive heating or other electrical conversion methods, eliminating the combustion process that produces carbon dioxide emissions. The system maintains the required heat balance by using electricity to generate the necessary thermal energy for steam generation and process heating, thereby decoupling heat production from carbon emissions.
3Productivity
If hydrocarbon feedstock is preheated to high temperatures before mixing with steam, then the evaporation rate is improved, but fouling potential increases
Solution Approach 1:
The patent applies preliminary heating action by preheating the hydrocarbon feedstock to an intermediate temperature (not the final high cracking temperature) before mixing with steam. This preliminary preheating reduces the temperature gap between the feedstock and the steam, improving the evaporation rate when they mix. The feedstock is then rapidly evaporated upon contact with the high-temperature steam, achieving complete vaporization without requiring the feedstock to be preheated to the final high temperature that would cause fouling.
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 method allows for efficient preheating and evaporation of hydrocarbon feedstocks without significant fouling, ensuring stable operation of electrical steam cracking furnaces and producing petroleum-derived products with reduced environmental impact.
Implementation Method 1
at least 90% of a heat amount used in said preheating the feed stream until its combination with the superheated dilution steam is provided by transferring heat from steam to the hydrocarbon feed stream
Implementation Method 2
steam cracking the steam cracking feed stream using a steam cracking arrangement operated with electric energy
Implementation Method 3
heated further to a temperature closer to a cracking temperature sufficient to carry out an endothermic reaction for cracking the hydrocarbons
Implementation Method 4
The cracked mixture may thereafter be fed to a heat exchanger to rapidly quench the cracked mixture to minimize undesired post-cracking reactions
Data Source
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AI summary
There is provided a method of steam cracking one or more hydrocarbons, the method comprising preheating a liquid hydrocarbon feed stream (1) containing the one or more hydrocarbons to provide a preheated hydrocarbon feed stream (2), superheating a dilution steam stream (3) to provide superheated dilution steam stream (4), combining the preheated hydrocarbon feed stream (2) and the superheated dilution steam stream (4) to provide a gaseous steam cracking feed stream (6), and steam cracking the gaseus steam cracking feed stream (6) using a steam cracking arrangement (F) operated with electric energy, wherein at least 90% of of a heat amount used in said preheating the hydrocarbon stream (1) until its combination with the superheated dilution steam (4) is provided by transferring heat from steam to the hydrocarbon feed stream (1). A corresponding system (100, 200, 300, 400) for steam cracking is also provided.