Parallel Methanol Reaction Units for Conversion Efficiency
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Solution Overview
Problem
The existing methanol synthesis processes face challenges with low methanol production yield due to the high reactivity of synthesis gas derived from natural gas or heavier hydrocarbons, leading to excessive by-product formation and low conversion efficiency per pass through the methanol catalyst, necessitating the recycling and dilution of synthesis gas.
Innovation Solution
The process employs two parallel reaction units, where the first unit operates on fresh synthesis gas mixed with recycled unconverted gas, and the second unit solely on recycled unconverted synthesis gas, optimizing catalyst performance and overall gas conversion efficiency while minimizing by-product formation, and utilizing a common circulator to reduce pressure loss by maintaining both units at the same pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high reactive synthesis gas is used for direct methanol synthesis, then methanol production rate is improved, but by-product formation increases and catalyst performance deteriorates
Solution Approach 1:
The synthesis gas conversion is divided into two separate reaction units operating in parallel. The first unit handles fresh synthesis gas with controlled reactivity, while the second unit processes recycled unconverted gas. This segmentation allows each unit to operate under optimized conditions, preventing excessive by-product formation while maintaining high overall methanol production efficiency.
2Object-generated harmful factors
If synthesis gas is diluted with recycle gas, then by-product formation is reduced, but conversion efficiency per pass decreases
Solution Approach 1:
The process separates the conversion of fresh synthesis gas and recycled gas into two distinct reaction units. The first unit maintains higher conversion efficiency by processing fresh gas with optimal composition, while the second unit handles diluted recycled gas at lower conversion rates, preventing by-product formation. This segmentation resolves the contradiction by allowing each unit to operate in its optimal efficiency range.
Solution Approach 2:
The system changes the operating parameters (gas composition, flow rate, conversion rate) for each reaction unit based on the specific characteristics of the feed gas. Fresh synthesis gas enters the first unit with parameters optimized for high conversion, while recycled gas enters the second unit with parameters optimized for low by-product formation, thus resolving the contradiction between conversion efficiency and by-product reduction.
3Productivity
If unconverted synthesis gas is recycled and diluted with fresh gas, then overall conversion is improved, but catalyst performance decreases due to repeated exposure to high reactive gas
Solution Approach 1:
The parallel two-unit configuration segments the catalyst exposure: the first unit's catalyst handles fresh synthesis gas with controlled reactivity, while the second unit's catalyst handles recycled gas. This segmentation prevents any single catalyst from being repeatedly exposed to highly reactive gas conditions, maintaining catalyst performance while achieving high overall conversion through the combined capacity of both units.
4Productivity
If multiple reactors are used in series, then conversion efficiency is improved, but equipment costs and catalyst volume increase
Solution Approach 1:
Instead of using identical reactors in series, the invention employs two parallel reactors with asymmetric functions: the first reactor is optimized for high conversion of fresh synthesis gas, while the second reactor is optimized for processing recycled gas with reduced by-product formation. This asymmetric parallel configuration achieves the conversion efficiency of series reactors while reducing equipment complexity and catalyst volume through parallel operation and optimized gas distribution.
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 results in reduced catalyst volume and lower equipment costs, achieving higher methanol synthesis efficiency and minimizing by-product formation, particularly beneficial for large-capacity plants requiring multiple reactors.
Implementation Method 1
catalytic conversion of methanol synthesis gas
Implementation Method 2
the circulator being arranged in the circulation passageway between the separating means and the split stream passageway for circulating the unconverted synthesis gas
Data Source
Figure 1
Figure 2
AI summary
Process and reaction system for the preparation of methanol comprising two reaction units, wherein a first unit is operated on a mixture of fresh synthesis gas and unconverted synthesis gas and a second unit solely with unconverted synthesis gas.