Pyrolysis Gas Compression Using an Independent Allam-Cycle CO2 Loop
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Solution Overview
Problem
Conventional olefin production plants face inefficiencies due to the coupling of production and recovery facilities, leading to decreased thermal efficiency and increased greenhouse gas emissions, particularly when pyrolysis reactors are taken offline unexpectedly.
Innovation Solution
Integrate a turbine operated based on the Allam cycle to power the process gas compressor independently from the pyrolysis process, using CO2 as a working fluid to minimize emissions and maintain system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steam turbine is used to power the process gas compressor using steam from the pyrolysis process, then the compressor can be powered independently, but the thermal efficiency decreases and CO2 emissions increase when the pyrolysis reactor is taken offline
Solution Approach 1:
The system is divided into two independent segments: the pyrolysis process and the power generation process. The Allam cycle power generator operates independently from the pyrolysis reactor, allowing the compressor to be powered continuously even when the pyrolysis reactor is offline. This segmentation resolves the contradiction by enabling reliable compressor operation without compromising thermal efficiency of the pyrolysis process.
Solution Approach 2:
The Allam cycle power generator acts as an intermediary between the pyrolysis process and the compressor. Instead of directly coupling the compressor to the pyrolysis steam system, the power generator converts natural gas chemical energy into mechanical energy to drive the compressor, eliminating the thermal efficiency losses associated with steam generation and transfer while ensuring continuous operation.
2Device complexity
If conventional steam cracking processes are used with coupled production and recovery facilities, then the system structure is simple, but thermal efficiency decreases and greenhouse gas emissions increase
Solution Approach 1:
The production facility (pyrolysis reactor) and recovery facility (compressor and separation equipment) are decoupled through the introduction of an independent Allam cycle power generator. This segmentation allows each facility to operate optimally without being constrained by the other, improving thermal efficiency while maintaining manageable system complexity through modular design.
Solution Approach 2:
The Allam cycle power generator serves multiple functions: it generates shaft power for the compressor, produces CO2 for potential reuse or sequestration, and can operate independently of the pyrolysis process. This multi-functionality improves thermal efficiency while the standardized power generation technology keeps system complexity manageable.
3Reliability
If additional steam generators are used to maintain compressor power when furnaces are taken offline, then compressor operation is maintained, but thermal efficiency further decreases
Solution Approach 1:
The Allam cycle power generator serves as an intermediary power source that replaces the need for additional steam generators. By converting natural gas directly into mechanical energy, it maintains compressor operation during furnace outages without the thermal efficiency penalties of generating and transferring steam, thereby resolving the contradiction between reliability and energy efficiency.
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 decouples the pyrolysis reactor from the process gas compressor, reducing CO2 and other greenhouse gas emissions while maintaining overall system efficiency, even during reactor outages.
Implementation Method 1
a turbine operated based on an Allam cycle to power the process gas compressor
Implementation Method 2
using CO2 as a working fluid
Implementation Method 3
conventional steam cracking processes typically produce light olefin by hydrocarbon pyrolysis
Data Source
AI summary
Processes, systems, and apparatus are provided for producing a compressed process gas comprising light olefin such as ethylene. The process utilizes a pyrolysis reactor to produce the process gas. A power generator utilizes a turbine operated based on an Allam cycle to produce shaft power for operating one or more compressors 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. Examples of using the shaft power for processing of the process gas can include compressing the process gas a process gas compressor powered by the produced shaft power and cooling the process gas using a refrigeration compressor powered by the produced shaft power.