Methanol Synthesis CO2 Recycling for Quantitative Carbon Utilization
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Solution Overview
Problem
Existing methanol production processes using synthesis gas result in significant carbon dioxide emissions and inefficient utilization of carbon dioxide and hydrogen, leading to unconverted gases and by-products that are not fully reused for further methanol synthesis.
Innovation Solution
A process that converts carbon dioxide and hydrogen into methanol using a low-pressure methanol synthesis unit, followed by a series of steps including expansion, distillation, and combustion to recycle carbon dioxide and hydrogen-containing streams, utilizing an oxygen-rich gas for combustion to minimize emissions and maximize methanol production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide and hydrogen are converted to methanol using low-pressure synthesis, then methanol production efficiency is improved, but unconverted gases and by-products are not fully reused leading to material loss
Solution Approach 1:
The patent recovers unconverted hydrogen and carbon dioxide from the synthesis off-gas through pressure swing adsorption and combustion units, converting them back to usable forms for continued methanol synthesis, thereby eliminating material loss while maintaining high production efficiency
Solution Approach 2:
The process implements a feedback loop where off-gas components are continuously analyzed and fed back into the synthesis system after treatment, ensuring optimal utilization of reactants and maintaining steady-state efficiency without material waste
2Quantity of substance
If synthesis gas is produced from natural gas or coal gasification, then methanol synthesis feedstock is obtained, but significant carbon dioxide emissions occur
Solution Approach 1:
The patent converts the harmful carbon dioxide emissions from synthesis gas production into a beneficial resource by capturing and recycling CO2 back into the methanol synthesis process, transforming an environmental liability into a valuable feedstock component
Solution Approach 2:
The combustion unit uses controlled oxidation with oxygen-rich gas to efficiently convert unconverted carbon monoxide and hydrogen into carbon dioxide, which is then recovered and reused, creating a closed-loop system that eliminates emissions while maintaining synthesis gas production
3Loss of energy
If off-gas streams are sent to thermal utilization, then energy recovery is achieved, but carbon dioxide emissions increase
Solution Approach 1:
The patent introduces a carbon dioxide recovery unit as an intermediary between the combustion process and the environment, capturing CO2 before it is emitted and redirecting it back to the synthesis process, thereby decoupling energy recovery from harmful emissions
4Loss of substance
If hydrogen is recovered through pressure swing adsorption, then unconverted hydrogen is reused, but the gas stream not absorbed requires thermal utilization
Solution Approach 1:
The patent makes the combustion unit multi-functional by using it both to generate thermal energy and to produce carbon dioxide for the synthesis process, eliminating the need for separate thermal utilization and associated emissions while maximizing hydrogen 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
The process achieves nearly complete conversion of carbon dioxide to methanol while minimizing carbon dioxide emissions, effectively reusing unconverted gases and by-products within existing methanol synthesis infrastructure.
Implementation Method 1
synthesis gas is converted under heterogeneous catalysis to methanol in a methanol synthesis reactor
Implementation Method 2
a methanol- and water-enriched crude methanol stream (II) is first condensed out of the reaction mixture
Implementation Method 3
feeding the carbon compounds in the streams separated off in the synthesis and isolation of the methanol, are converted to carbon dioxide
Implementation Method 4
The further methanol-enriched liquid stream that remains after the outgassing is then subjected to a multistage distillation for the actual methanol recovery
Data Source
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AI summary
A process for preparing methanol from carbon dioxide and hydrogen in a methanol synthesis unit and working up the reaction mixture obtained stepwise to isolate the methanol, wherein the carbon dioxide, carbon monoxide, dimethyl ether and methane components of value from the streams separated off in the isolation of the methanol from the methanol reaction stream are combusted with an oxygenous gas, and the carbon dioxide in the resultant flue gas is separated off in a carbon dioxide recovery unit and recycled to the methanol synthesis unit.