Lubricated Steam Expander Using Ionic Liquid Phase Separation
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Solution Overview
Problem
In steam cycle processes with expanders, the separation of lubricants from working media is challenging due to heat sensitivity and miscibility issues, leading to contamination and premature aging of lubricants, which affects the efficiency and longevity of the process.
Innovation Solution
The use of ionic liquids as lubricants, which form two liquid phases with the working medium at room temperature, allowing for effective separation through techniques such as density difference, mechanical means, coalescence filters, and demulsifiers, ensuring minimal solubility and vapor pressure, thereby preventing lubricant decomposition and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lubricants are used in steam cycle expanders, then the expander components can be lubricated, but the lubricant mixes with the working medium and cannot be separated, leading to contamination and premature aging
Solution Approach 1:
The patent changes the chemical and physical parameters of the lubricant by using ionic liquids instead of conventional lubricants. This parameter change enables the lubricant to form immiscible phases with the working medium, allowing for effective separation and preventing contamination while maintaining lubrication functionality.
Solution Approach 2:
The patent utilizes phase separation between the ionic liquid lubricant and the working medium. The lubricant and working medium form distinct liquid phases that can be separated based on their immiscibility, enabling effective separation downstream of the expander and preventing lubricant degradation from contamination.
2Stability of the object's composition
If heat-sensitive lubricants are used, then the lubricant can maintain stability at lower temperatures, but the lubricant decomposes when exposed to high temperatures in the evaporator
Solution Approach 1:
The patent extracts the lubricant from the high-temperature zone by implementing effective separation downstream of the expander and upstream of the evaporator. This extraction prevents the heat-sensitive lubricant from being exposed to decomposing temperatures in the evaporator, maintaining its compositional stability.
Solution Approach 2:
The patent introduces a separator as an intermediary component between the expander and evaporator. This separator acts as a mediator to remove the lubricant from the working medium stream before it enters the evaporator, protecting the heat-sensitive lubricant from thermal degradation.
3Reliability
If the lubricant is separated upstream of the evaporator, then the lubricant can be protected from decomposition, but the separation process becomes complex
Solution Approach 1:
The patent enables the lubricant-working medium mixture to self-separate into immiscible phases through density differences and phase separation properties. This self-service separation mechanism reduces the need for complex external separation systems, protecting the lubricant while minimizing device complexity.
Solution Approach 2:
The patent changes the physical parameters of the lubricant by using ionic liquids with specific density and phase separation characteristics. These parameter changes enable effective separation through simple gravity-based or centrifugal separation methods, protecting the lubricant without requiring complex separation equipment.
4Ease of operation
If conventional lubricants with vapor pressure are used, then the lubricant can be transported in the circuit, but the lubricant vapor cannot be separated from the working medium vapor
Solution Approach 1:
The patent changes the vapor pressure parameter of the lubricant by using ionic liquids with negligible vapor pressure. This parameter change eliminates the vapor phase of the lubricant, making vapor separation unnecessary while maintaining liquid-phase circulation and transport capabilities in the system.
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 enables reliable separation of lubricants from the working medium, preventing contamination and ensuring the lubricant's properties are maintained, thus enhancing the operational reliability and longevity of the steam cycle process.
Implementation Method 1
which liquid forms two liquid phases with the liquid working medium (A) at room temperature
Implementation Method 2
the ionic liquid forming the lubricant for the expander (5) is separated from the working medium (A) upstream of the evaporator (1)
Data Source
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AI summary
The invention relates to a method for operating a steam cycle process which is performed in an apparatus according to the invention, which has an evaporator (1) or steam generator for the evaporation of a liquid working medium (A) and an expander (5), which is lubricated by means of a lubricant, for the performance of mechanical work, the method comprising the following method steps: a) the liquid working medium (A) is fed to the evaporator (1), in which it evaporates and is fed to the expander (5) in the form of steam; b) an ionic liquid (B), which at room temperature forms two liquid phases with the liquid working medium (A), is also fed to the expander (5) as a lubricant; and c) the ionic liquid forming the lubricant for the expander (5) is separated from the working medium (A) upstream of the evaporator (1).