Methane Reactor Ejector Pressure Compensation
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Solution Overview
Problem
The existing methods for producing methane from synthesis gas face efficiency and cost issues due to temperature-related methane yield decreases and catalyst aging, particularly when using steam as a motive medium in ejectors, which also reduce pressure and methane yield.
Innovation Solution
Compressing the product-gas stream to a higher pressure than the synthesis gas and using it as the motive medium in an ejector, or utilizing gas from a natural-gas transmission network, to maintain pressure and prevent catalyst aging, while allowing for efficient methane production and integration with natural-gas transmission systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If steam is used as the motive medium in the ejector, then the ejector can be operated at elevated temperatures, but the catalyst aging is accelerated and methane yield is reduced
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary device between the reactor and the ejector. This heat exchanger cools the synthesis gas before it enters the ejector, allowing the ejector to operate at lower temperatures that do not accelerate catalyst aging, while still maintaining the temperature compensation function. The heat exchanger mediates between the high-temperature reactor outlet and the temperature-sensitive ejector and catalyst.
2Ease of operation
If the synthesis gas pressure is reduced in the ejector, then the recycle gas can be conveyed, but the methane yield is reduced due to reaction equilibria
Solution Approach 1:
The patent replaces the traditional mechanical compressor with an ejector that uses fluid dynamics principles. The ejector uses a high-velocity fluid stream to create a pressure difference that drives the recycle gas back to the reactor inlet, eliminating the need for mechanical compression and avoiding the pressure reduction that would occur in a compressor system.
Solution Approach 2:
The patent changes the pressure parameter profile in the system by using an ejector design that maintains higher pressure levels compared to traditional compressor-based systems. The ejector creates a more favorable pressure distribution that allows recycle gas conveyance while maintaining pressure levels that favor methane production equilibrium.
3Stress or pressure
If a compressor is used to compensate pressure drops, then the pressure can be maintained, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the compression function from the traditional mechanical compressor and redistributes it across the ejector system. The ejector uses the kinetic energy of the motive fluid to create the necessary pressure compensation, eliminating the need for a separate mechanical compressor and reducing overall system complexity.
Solution Approach 2:
The patent uses pneumatic principles through the ejector design, where a high-velocity gas stream creates a pressure difference that drives the recycle gas. This pneumatic approach replaces mechanical compression with fluid dynamic pressure generation, simplifying the system by eliminating mechanical moving parts in the compression stage.
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 methane yield and reduces costs by maintaining reactor pressure, preventing catalyst aging, and enabling efficient integration with natural-gas transmission networks, thereby improving the overall efficiency and economic viability of the process.
Implementation Method 1
the approach is therefore known whereby the process gas stream leaving the reactor is divided into a product-gas stream and a recycle-gas stream and the previously cooled recycle gas is then returned to the inlet of the reactor. When the recycle gas is recirculated, the pressure drops that occur must be compensated for. Using a compressor for this purpose creates the problem that it can only be designed for increased temperatures of around 300° C. at considerable cost
Implementation Method 2
the pressure drops that occur must be compensated for
Implementation Method 3
a synthesis gas containing carbon monoxide and hydrogen is supplied to a reactor including a catalyst to effect methanation
Implementation Method 4
Conversion of carbon monoxide and hydrogen to form methane is effected first by the equation CO+3H2→CH4+H2O
Implementation Method 5
The methanation in the presence of a catalyst proceeds in a highly exothermic fashion
Implementation Method 6
the product-gas stream is compressed to a pressure that is greater than the pressure of the synthesis gas supplied to the reactor
Data Source
AI summary
The invention relates to a process for producing a methane-containing gas from synthesis gas, wherein a synthesis gas containing carbon monoxide and hydrogen is fed for methanation to a reactor system (1) having a catalyst material, wherein the process gas stream leaving the reactor system (1) is divided into a product gas stream and a recycle gas stream, and wherein the recycle gas stream, for compensation of the pressure drop, is transported through an ejector (5) and for cooling is passed together with the synthesis gas into the reactor system (1). According to the invention, the product gas stream is compressed to a pressure which is greater than the pressure of the synthesis gas that is fed to the reactor system (1). Either compressed product gas or industrial gas from an industrial gas pipe system (9) is fed as propellant medium to the ejector (5). The invention also relates to a methane production plant for carrying out the process.