CO2 Working-Fluid Integration in Pyrolysis Furnaces to Cut Emissions
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Solution Overview
Problem
Hydrocarbon pyrolysis processes, such as steam cracking, produce significant greenhouse gas emissions, particularly CO2, due to the high energy requirements and inefficient heat recovery, and existing methods to reduce these emissions are costly and impractical.
Innovation Solution
Integrate a pyrolysis reactor with a turbine using a CO2-containing working fluid based on the Allam cycle, allowing for a common working fluid to power the process train and furnace, reducing CO2 emissions by operating the pyrolysis furnace at elevated pressures and using a CO2-rich working fluid for both the turbine and pyrolysis reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrocarbon pyrolysis is performed using conventional steam cracking with combustion for energy supply, then useful products such as light olefin are produced, but significant CO2 exhaust emissions are generated
Solution Approach 1:
The patent captures CO2 from pyrolysis effluent and combustion exhaust, then uses it as a working fluid in a turbine cycle to generate power. The harmful CO2 emission is converted into a useful resource for power generation, simultaneously reducing emissions and providing energy for the pyrolysis process
Solution Approach 2:
The patent integrates the pyrolysis effluent processing train with the furnace by using a common CO2 working fluid loop. The CO2 captured from pyrolysis effluent is combined with CO2 from combustion exhaust, and this merged stream is used to power turbines that drive compressors and refrigeration equipment, creating a unified system that reduces overall CO2 emissions
2Object-generated harmful factors
If amine treatment is used to remove CO2 from combustion exhaust, then CO2 emissions are reduced, but the cost increases significantly due to the dilute nature of exhaust gas
Solution Approach 1:
Instead of treating CO2 as a waste product to be removed, the patent captures it and uses it as a valuable working fluid for power generation. The CO2 that would otherwise require expensive treatment is converted into a resource that drives turbines and generates power, eliminating the need for costly amine treatment of combustion exhaust
3Productivity
If high temperatures are used for hydrocarbon pyrolysis, then cracking efficiency is improved, but heat recovery opportunities are limited
Solution Approach 1:
The patent changes the working fluid parameters by using CO2 instead of conventional steam or air. CO2 has superior heat transfer properties at high temperatures, enabling more effective heat recovery from the pyrolysis process. The system operates the turbine cycle at parameters that optimize both the cracking efficiency and heat recovery from the high-temperature effluent
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 integration reduces CO2 emissions by minimizing low-pressure CO2 exhaust, improves energy efficiency, and enables efficient heat transfer, resulting in a more environmentally friendly and cost-effective hydrocarbon pyrolysis process.
Implementation Method 1
a CO2-containing working fluid powers turbines for the process train and furnace, reducing CO2 emissions by operating within a common working loop and increasing pressure to enhance heat transfer efficiency
Implementation Method 2
a CO2-containing working fluid powers turbines for the process train and furnace
Implementation Method 3
Hydrocarbon pyrolysis processes, e.g., steam cracking, produce commercially-important amounts of useful products and co-products, such as saturated and unsaturated hydrocarbon
Data Source
AI summary
Processes, systems, and apparatus are provided for using a common working fluid for one or more turbines for processing a process gas and for the furnace for the pyrolysis process used to produce the process gas. The turbine(s) are operated based on a modified Allam cycle to produce power for operating one or more compressors and/or refrigerators involved in processing of the process gas while producing a reduced or minimized amount of CO2 that is released as a low-pressure gas phase product. Integrating the pyrolysis furnace with the working fluid loop can provide further benefits.