Methanol Synthesis Loop Tail Gas Reforming
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Solution Overview
Problem
Conventional biomass gasification processes for methanol production retain high concentrations of methane in syngas, leading to reduced plant productivity and efficiency, as well as increased operational costs due to the need for methanol purification and water treatment.
Innovation Solution
A process and plant design that recycles methane and aqueous streams within the methanol synthesis loop, where methane from the tail gas is converted into additional synthesis gas through reforming, and aqueous streams are reused without the need for purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional biomass gasification is carried out at low temperature and high pressure, then methanol synthesis conditions are achieved, but methane content in syngas remains high (10-12% mol)
Solution Approach 1:
The patent changes the operating parameters of the gasification process, specifically operating at temperatures above 1000°C (e.g., 1000-1500°C) and pressures below 30 bar (e.g., 1-20 bar), which are different from conventional conditions. These parameter changes reduce methane formation during gasification while still producing syngas suitable for methanol synthesis after adjustment.
Solution Approach 2:
The patent introduces a dynamic approach by adjusting syngas composition through controlled oxidation and addition of external agents (oxygen, air, or steam) to modify the H2/CO ratio and reduce methane content. This dynamic adjustment allows the system to adapt syngas composition to optimal levels for methanol synthesis.
2Productivity
If high methane content syngas is used for methanol synthesis, then synthesis can proceed, but plant productivity and efficiency are reduced due to unconverted methane being purged
Solution Approach 1:
The patent implements a feedback mechanism where tail gas containing unconverted methane and other components is recycled back to the gasification process. This feedback loop allows unconverted methane to be reprocessed and converted into additional syngas, which is then fed back into the methanol synthesis loop, thereby reducing energy loss and improving overall productivity.
3Manufacturing precision
If methanol purification is carried out in a distillation section, then high purity methanol is obtained, but operational costs increase and resources are wasted due to aqueous stream discharge
Solution Approach 1:
The patent converts the harmful waste stream (aqueous stream containing residual methanol and impurities) into a beneficial resource by recycling it back to the gasification process. This eliminates the need for costly purification and discharge operations, while the aqueous stream serves as a useful input for further methanol production, thereby converting a waste problem into a productivity advantage.
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 enhances energy efficiency, reduces operational costs, and increases methanol productivity by approximately 30% compared to conventional methods, while also improving carbon efficiency and minimizing water loss.
Implementation Method 1
a reforming unit for converting the甲烷 retained in said tail gas into a second stream of synthesis gas
Implementation Method 2
catalytic conversion of carbon oxides to methanol is carried out under methanol synthesis conditions
Implementation Method 3
A gasification process involves the partial oxidation of a carbonaceous feedstock in presence of a sub-stoichiometric amount oxidant
Data Source
AI summary
Process for the synthesis of methanol comprising the steps of: subjecting a biomass to a gasification process in presence of steam and an oxidant; subjecting the so obtained gasifier stream to water gas shift conversion and purification to yield a synthesis gas with hydrogen, carbon monoxide and CO2; mixing said synthesis gas with a second stream of synthesis gas to yield a third stream of synthesis gas; feeding said third stream of synthesis gas to a methanol synthesis loop wherein a crude methanol and a tail gas retaining methane are produced; subjecting said tail gas to a reforming step in presence of an oxidant to generate said second stream of synthesis gas.