Process for the purification of raw gases by means of physical gas scrubbing
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Solution Overview
Problem
The Rectisol process for separating acidic gas constituents like carbon dioxide and hydrogen sulfide from raw synthesis gas is energy-intensive due to suboptimal heat transfer between methanol and traditional one-component coolants like ammonia or propylene.
Innovation Solution
A multi-component coolant composition of 5 to 15 mol-% ethylene, 5 to 15 mol-% n-butane, 30 to 60 mol-% propylene is used, which provides a continuous evaporation temperature profile, enhancing heat transfer efficiency and reducing energy consumption by increasing the mean temperature difference between the coolant and methanol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional one-component coolants like ammonia or propylene are used in the compression refrigeration machine, then the cooling function is achieved, but the heat transfer efficiency is suboptimal and energy consumption is high
Solution Approach 1:
The patent applies composite materials principle by using a multi-component coolant composition instead of traditional single-component coolants. The coolant comprises propylene (30-60 mol%), propane (30-40 mol%), and n-butane (5-15 mol%), creating a composite refrigerant mixture that optimizes heat transfer properties and reduces energy consumption in the compression refrigeration machine while maintaining the required cooling function
2Productivity
If the mean temperature difference between coolant and methanol is increased to improve heat transfer efficiency, then energy consumption is reduced, but the temperature control complexity increases
Solution Approach 1:
The patent applies parameter changes principle by optimizing the compositional parameters of the coolant mixture. By adjusting the molar percentages of propylene, propane, and n-butane within specific ranges, the mean temperature difference between coolant and methanol is optimized to enhance heat transfer efficiency. The multi-component composition provides a continuous evaporation temperature profile that maintains optimal temperature differential throughout the heat exchanger, improving productivity while the parameter ranges are set to balance efficiency with controllability
3Power
If a multi-component coolant composition is used to enhance heat transfer efficiency, then compressor capacity and cooling water requirements are reduced, but the coolant formulation complexity increases
Solution Approach 1:
The patent uses composite materials principle with a three-component coolant mixture where propylene (30-60 mol%), propane (30-40 mol%), and n-butane (5-15 mol%) work synergistically. This composite formulation reduces compressor capacity requirements and cooling water consumption compared to single-component coolants, while the specific component ranges are designed to maintain formulation manageability
Solution Approach 2:
The patent optimizes the power parameter by changing the coolant composition parameters. The multi-component mixture with specific molar ratios improves vaporization characteristics and heat transfer coefficients, leading to reduced compressor capacity requirements. The parameter optimization balances the trade-off between formulation complexity and power 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
This approach reduces energy expenditure by achieving a defined temperature decrease with less energy, resulting in significant compressor capacity savings and reduced cooling water requirements, while maintaining safe and non-toxic properties.
Implementation Method 1
A multi-component coolant composition of 5 to 15 mol-% ethylene, 5 to 15 mol-% n-butane, 30 to 60 mol-% propylene is used, which provides a continuous evaporation temperature profile, enhancing heat transfer efficiency
Implementation Method 2
enhancing heat transfer efficiency and reducing energy consumption by increasing the mean temperature difference between the coolant and methanol
Implementation Method 3
Cooling of the coolant is effected in a compression refrigeration machine with mostly several compressor stages
Implementation Method 4
The compressed coolant vapor is condensed in a first cooling stage by indirect heat exchange
Data Source
Figure 1
AI summary
A process for separating undesired, in particular acidic gas constituents from a raw gas, in particular raw synthesis gas, by absorption with cold methanol as physical detergent, wherein the methanol is cooled in a compression refrigeration machine by using a multi-component coolant. The use of the coolant according to the invention provides significant advantages with regard to the compressor capacity required in the compression refrigeration machine for the provision of a defined cooling capacity.