Methanation Heat Integration for Steam Turbine Efficiency
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Solution Overview
Problem
Methanation processes require additional steam to be added to the shift reactor due to insufficient moisture content in syngas exiting the radiant synthesis gas cooler, leading to inefficient heat recovery and increased energy losses.
Innovation Solution
An integrated system that combines methanation and steam turbine processes, utilizing an optimized gasifier with a radiant syngas cooler and quench chamber to achieve a desirable steam-to-dry gas ratio, eliminating the need for additional steam and enhancing heat recovery through energy integration between gasification, methanation, and steam turbine systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If steam is added to the shift reaction process to achieve desired steam-to-dry gas ratio, then the methanation process can proceed, but energy losses increase and heat recovery efficiency decreases
Solution Approach 1:
The patent merges the gasification process with the methanation process by integrating the gasifier outlet directly with the methanation reactor inlet. This integration allows the hot syngas from gasification to directly feed the methanation reaction, eliminating the need for separate steam addition and recovering heat that would otherwise be lost in traditional isolated processes.
Solution Approach 2:
The patent changes the operational parameters by maintaining higher temperatures in the methanation reactor (800-1000°C) and adjusting the steam-to-dry gas ratio dynamically based on the actual syngas composition from the gasifier. This allows optimization of the methanation reaction while minimizing additional steam input and associated energy losses.
2Reliability
If steam is added to moisturize syngas for the shift reaction, then the catalyst can function properly, but heat recovery efficiency is reduced
Solution Approach 1:
The system makes itself self-sufficient by using the hot syngas from the gasifier to directly feed the methanation reactor, eliminating the need for external steam addition. The process self-regulates the moisture content and temperature requirements for catalyst function through the inherent heat and mass transfer in the integrated reactor system.
Solution Approach 2:
The patent converts the typically harmful effect of hot syngas (which would normally require cooling and steam addition) into a beneficial resource by directly using it to drive the methanation reaction. The heat that would normally be wasted or require steam compensation is instead utilized to maintain optimal reaction conditions.
3Device complexity
If traditional isolated gasification and methanation processes are used, then process simplicity is maintained, but energy losses increase
Solution Approach 1:
The patent combines traditionally separate gasification and methanation units into a single integrated process flow. The gasifier outlet is directly connected to the methanation reactor inlet, creating a continuous process that eliminates intermediate cooling and steam addition steps, thereby reducing energy losses while maintaining reasonable process complexity.
Solution Approach 2:
The integrated reactor system performs multiple functions simultaneously: it conducts gasification, moisture conditioning, and methanation reactions in sequence without requiring separate dedicated units for each function. This multi-functionality reduces overall energy requirements and improves heat recovery 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 integrated system achieves optimal steam-to-dry gas ratios without additional steam input, reducing energy losses and improving heat recovery efficiency, thereby optimizing the methanation process and enhancing energy utilization.
Implementation Method 1
a low-pressure superheater coupled between the second reactor and the third reactor that heats low-pressure steam
Implementation Method 2
a low-pressure steam turbine having an input coupled to an output of the low-pressure superheater
Implementation Method 3
Methanation is a physical-chemical process to generate methane from a mixture of various gases out of biomass fermentation or thermo-chemical gasification
Data Source
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Figure 2
AI summary
A combined gasification, methanation and power island steam turbine system (100). The system includes a methanation portion (202), and a steam turbine portion (204). The methanation portion includes the new heat recovery design and associated controls for obtaining a desired steam to dry gas ratio of 1.1-2.2. The methanation portion includes first (214), second (216) and third (218) methanation reactors and associated heat recovery integrated with a high -pressure, low-pressure superheater, and HP economizers.. The power Island steam turbine includes turbines an input coupled to an output of the superheaters in Methanation process.