Steam Cracking Furnace Combustion Air Preheating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In steam cracking processes, high air preheating temperatures lead to difficulties in the design and operation of the downstream convection zone, resulting in reduced availability of exhaust gas heat, increased construction effort, and reduced thermal efficiency.
Innovation Solution
The method involves using feed water for preheating combustion air, which involves intermediate cooling of the feed water upstream of its preheating in the convection zone, allowing for maximum energy recovery from flue gas with minimal structural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high air preheating temperatures are used, then energy recovery from flue gas is improved, but the design and operation of the downstream convection zone becomes difficult
Solution Approach 1:
The patent introduces an intermediary cooling stage for the combustion air before it enters the convection zone. A portion of the combustion air is cooled from the high preheating temperature (e.g., 800-1000°C) to a lower temperature (e.g., 200-400°C) using a heat exchanger that utilizes process steam or cooling water as the cooling medium. This intermediary cooling step enables the downstream convection zone to operate within optimal temperature ranges, avoiding the difficulties associated with direct high-temperature operation while still achieving high energy recovery from the flue gas.
2Loss of energy
If high air preheating temperatures are used, then energy recovery from flue gas is improved, but construction effort increases
Solution Approach 1:
The patent employs an intermediary cooling system that utilizes existing process streams (process steam or cooling water) as the cooling medium. This approach avoids the need for entirely new high-temperature heat recovery systems and instead integrates the cooling function into the existing process infrastructure. The heat exchanger can be configured to recover heat from the high-temperature combustion air and transfer it to the process steam or cooling water, thereby achieving energy recovery without requiring extensive new construction.
3Loss of energy
If high air preheating temperatures are used, then energy recovery from flue gas is improved, but thermal efficiency is reduced
Solution Approach 1:
The patent applies parameter changes by adjusting the temperature of the combustion air at different stages of the process. The combustion air is preheated to a high temperature (800-1000°C) to maximize energy recovery from the flue gas, then a portion of it is cooled to a lower temperature (200-400°C) before entering the convection zone. This dynamic temperature adjustment optimizes both energy recovery and thermal efficiency, as the convection zone operates with air at a temperature that maintains efficient heat transfer and combustion conditions.
4Loss of energy
If high air preheating temperatures are used, then energy recovery from flue gas is improved, but operational complexity increases
Solution Approach 1:
The patent introduces an intermediary cooling stage that simplifies the operation of the overall system. By cooling a portion of the combustion air to a lower temperature before it enters the convection zone, the system avoids the operational difficulties associated with maintaining and controlling very high temperatures throughout the entire process. The heat exchanger can be operated using existing process steam or cooling water, which are already part of the normal process flow, thereby minimizing additional operational complexity while still achieving high energy recovery.
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 enables a compact design of the convection zone, reduced fuel requirements, and maximum production of superheated steam, while minimizing carbon dioxide emissions and operational complexity.
Implementation Method 1
the feed water is subjected to feed water preheating in one or more convection zones of the one or more cracker furnaces
Implementation Method 2
heat transfer means which are designed to transmit heat at least occasionally to the combustion air which is withdrawn from at least a portion of the feed water upstream of the feed water preheating
Data Source
AI summary
A method for reacting one or more hydrocarbons by steam cracking including conducting one or more input streams containing the one or more hydrocarbons, obtaining one or more product streams, through one or more radiation zones of one or more cracker furnaces, in which the one or more radiation zones are heated by firing heating gas with combustion air, in which at least a portion of the combustion air is subjected to combustion air preheating in which steam is produced from feed water, and in which the feed water is subjected to feed water preheating in one or more convection zones of the one or more cracker furnaces. The combustion air preheating is carried out at least in part and/or at least temporarily using heat withdrawn from at least part of the feed water upstream of the feed water preheating.