OCM Methane Recycling for Lower-Energy Olefin Separation
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Solution Overview
Problem
The petrochemical industry faces inefficiencies in converting methane to higher chain hydrocarbons due to limitations in existing cracking and fractionation technologies, which are energy-intensive and produce significant greenhouse gases, and there is a need for alternative feedstocks to crude oil to produce hydrocarbon intermediates and fuels.
Innovation Solution
An oxidative coupling of methane (OCM) system that processes methane with an oxidizing agent to produce C2+ compounds, including alkanes and alkenes, using a subsystem with heat exchangers, de-methanizers, and hydrogenation units to separate and convert these products, along with a methanation subsystem to recycle methane and reduce impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional steam cracking methods are used to produce ethylene from hydrocarbons, then ethylene production is achieved, but energy consumption is high and greenhouse gas emissions are significant
Solution Approach 1:
The patent changes the fundamental reaction parameters by using oxidative coupling of methane instead of steam cracking, operating at lower temperatures (700-900°C vs 800-900°C) with controlled oxygen partial pressures to achieve selective C2+ hydrocarbon formation while reducing overall energy consumption and CO2 emissions
Solution Approach 2:
The patent introduces controlled oxidation using oxygen or air as the oxidizing agent in the OCM process, enabling selective oxidation of methane to C2+ hydrocarbons (ethylene, ethane, propane, butane) while minimizing complete combustion, thus reducing energy consumption compared to traditional steam cracking
2Productivity
If traditional steam cracking methods are used to produce ethylene from hydrocarbons, then ethylene production is achieved, but greenhouse gas emissions are significant
Solution Approach 1:
The patent changes the fundamental reaction parameters by using oxidative coupling of methane instead of steam cracking, operating at lower temperatures (700-900°C vs 800-900°C) with controlled oxygen partial pressures to achieve selective C2+ hydrocarbon formation while reducing overall energy consumption and CO2 emissions
Solution Approach 2:
The patent converts the harmful effect of methane (a potent greenhouse gas) into beneficial C2+ hydrocarbons through oxidative coupling, thereby reducing methane emissions while producing valuable ethylene and other hydrocarbon products
3Use of energy by moving object
If OCM system is used to convert methane to C2+ hydrocarbons, then energy consumption is reduced and greenhouse gas emissions are reduced, but process complexity increases due to multiple separation and conversion units
Solution Approach 1:
The patent segments the OCM process into distinct functional units: OCM reaction zone, cooling section, de-methanizer, hydrogenation unit, and methanation subsystem, allowing each unit to be optimized independently for its specific function while managing overall process complexity
Solution Approach 2:
The patent implements recovery and recycling of unreacted methane through the de-methanizer and methanation subsystem, where methane is separated from C2+ products and recycled back to the OCM reactor, reducing feedstock requirements and improving overall process efficiency despite increased complexity
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 OCM system efficiently converts methane to valuable C2+ hydrocarbons, reducing energy consumption and greenhouse gas emissions while providing a viable alternative to traditional steam cracking methods, enhancing the production of ethylene and other hydrocarbon derivatives.
Implementation Method 1
An oxidative coupling of methane (OCM) reaction is a process by which methane can form one or more C2+ compounds
Implementation Method 2
the first heat exchanger cools the product stream
Implementation Method 3
the de-methanizer unit accepts the product stream from the first heat exchanger and generates an overhead stream comprising methane and at least a portion of the non-C2+ impurities, and a bottoms stream comprising at least a portion of the C2+ compounds
Implementation Method 4
at least a portion of the overhead stream is cooled in the second heat exchanger
Implementation Method 5
a hydrogenation unit downstream of the de-methanizer, wherein the hydrogenation unit accepts a stream comprising the C2+ compounds and hydrogenates alkynes in the C2+ compounds to alkanes and/or alkenes
Implementation Method 6
a methanation subsystem downstream of, and fluidically coupled to, the OCM subsystem, wherein the methanation subsystem reacts H2 and CO and/or CO2 included in the non-C2+ impurities to generate methane
Data Source
AI summary
The present disclosure provides oxidative coupling of methane (OCM) systems for small scale and world scale production of olefins. An OCM system may comprise an OCM subsystem that generates a product stream comprising C2+ compounds and non-C2+ impurities from methane and an oxidizing agent. At least one separations subsystem downstream of, and fluidically coupled to, the OCM subsystem can be used to separate the non-C2+ impurities from the C2+ compounds. A methanation subsystem downstream and fluidically coupled to the OCM subsystem can be used to react H2 with CO and/or CO2 in the non-C2+ impurities to generate methane, which can be recycled to the OCM subsystem. The OCM system can be integrated in a non-OCM system, such as a natural gas liquids system or an existing ethylene cracker.