Syngas Methane Recovery via Partial Oxidation Reforming
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Solution Overview
Problem
The production of biofuels from lignocellulosic biomass is hindered by the recalcitrant nature of lignocellulosic materials, which require complex pretreatment and hydrolysis steps, and the inefficiency of anaerobic microorganisms in converting syngas components like CO and H2 to liquid products, especially due to high methane content in syngas from indirect gasification processes.
Innovation Solution
A process that utilizes bioconversion to separate and efficiently recover methane from syngas, converting it back into CO and H2 through partial oxidation reforming, allowing for high utilization of methane in bioconversion processes to produce ethanol and other liquid products, while maintaining compatibility with bioreactor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If syngas from indirect gasification is used directly for bioconversion, then the process can utilize high methane content syngas, but the methane must be converted back to CO and H2 which requires additional energy input and process complexity
Solution Approach 1:
The process divides the syngas stream into two separate streams: a first syngas stream that is directly converted to liquid products, and a second syngas stream containing methane that is separately converted to CO and H2 through partial oxidation. This segmentation allows each stream to be processed according to its specific composition requirements, resolving the contradiction by enabling methane utilization while managing process complexity through systematic separation.
Solution Approach 2:
A partial oxidation unit is introduced as an intermediary component between the methane-containing syngas stream and the bioconversion process. This intermediary converts methane into CO and H2, which are then usable by anaerobic microorganisms. The intermediary resolves the contradiction by providing a bridge that enables methane utilization without directly complicating the main bioconversion process.
2Productivity
If methane is converted back to CO and H2 through partial oxidation reforming, then methane can be utilized in bioconversion processes, but energy input and operational costs increase
Solution Approach 1:
The process converts methane, which is typically considered an unusable byproduct in indirect gasification, into a valuable resource. Through partial oxidation, methane is converted to CO and H2, which are then used to produce liquid biofuels. This transforms the harmful/unusable methane into a beneficial input, resolving the contradiction by enabling productive utilization while managing energy input through efficient conversion.
Solution Approach 2:
The partial oxidation unit changes the chemical composition parameters of the syngas stream by converting methane into CO and H2. This parameter change enables the gas to be utilized by anaerobic microorganisms that cannot directly process methane. The parameter change resolves the contradiction by transforming the chemical nature of methane into a form that can be productively utilized.
3Ease of manufacture
If conventional pretreatment and hydrolysis steps are used for lignocellulosic biomass, then bioconversion can proceed, but the process becomes complex and less efficient
Solution Approach 1:
The process extracts and removes the methane component from the syngas stream through selective conversion in the partial oxidation unit. By taking out methane and converting it to CO and H2, the process simplifies the remaining gas composition for bioconversion, resolving the contradiction by removing the problematic component while maintaining feasibility.
Solution Approach 2:
Instead of using conventional pretreatment and hydrolysis to break down lignocellulosic biomass before fermentation, the process inverts the approach by using gasification to convert biomass directly to syngas, then using partial oxidation to convert methane in the syngas to usable forms. This inversion eliminates the complex pretreatment steps while maintaining bioconversion feasibility.
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 the effective utilization of high methane-containing syngas, reducing operational costs and energy input, and enhances the efficiency of bioconversion processes by converting methane into usable syngas components, thereby increasing the production of liquid products like ethanol.
Implementation Method 1
gasification of the feed to syngas comprising CO2, CO, H2 and CH4
Implementation Method 2
bioconversion processes can be used to simply and efficiently separate the methane from the syngas... convert CO and H2/CO2 to high conversion to make products such as ethanol, acetic acid, butanol etc.
Implementation Method 3
passes at least a portion of the CH4 rich stream to a partial oxidation reformer to produce a reformed gas stream comprising CO and CO2 and H2
Data Source
AI summary
Ethanol and other liquid products are produced from biomass using indirect gasification of the biomass to produce a syngas containing CO2, CO, H2 and methane that passes the syngas without substantial removal of the methane to a fermentation zone for the conversion of the CO and CO2 and H2 to ethanol and the production of a methane rich stream followed by the methane reforming of the methane rich stream to produce additional CO and CO2 and H2 that passes to the fermentation zone.