Refrigerator Recycling System Using Membrane Separation
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Solution Overview
Problem
The challenge in recycling refrigerators is the recovery of volatile hydrocarbons like CFCs and pentane from insulation materials and refrigeration circuits while ensuring an environmentally friendly, energy-efficient, and cost-effective process.
Innovation Solution
A refrigerator recycling plant with a sealed process chamber, inert gas source, dehumidification cooling, compression, and membrane separation system that liquefies hydrocarbons at non-cryogenic temperatures, using a mechanical shredding device and heat exchangers to enhance gas release and separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If cryogenic cooling is used to separate hydrocarbons, then hydrocarbon recovery efficiency is improved, but energy consumption increases and system complexity increases
Solution Approach 1:
The patent changes the temperature parameter from cryogenic ranges to non-cryogenic ranges (above 0°C), and adjusts pressure parameters to achieve hydrocarbon liquefaction and separation under milder conditions. This is accomplished through the membrane device that concentrates hydrocarbons followed by cooling and compression steps, resolving the contradiction by achieving effective separation without the high energy costs of cryogenic cooling.
Solution Approach 2:
The patent replaces the cryogenic cooling mechanical system with a membrane-based separation system combined with mild cooling and compression. The membrane device (permeation barrier) provides the primary separation mechanism, substituting the need for extensive cryogenic infrastructure and reducing overall system complexity while maintaining hydrocarbon recovery efficiency.
2Loss of substance
If cryogenic cooling is used to separate hydrocarbons, then hydrocarbon recovery efficiency is improved, but device complexity increases
Solution Approach 1:
The patent replaces the complex cryogenic cooling system with a membrane device followed by simple cooling and compression equipment. The membrane separation module provides efficient hydrocarbon concentration without requiring cryogenic infrastructure, significantly reducing device complexity while maintaining recovery efficiency.
Solution Approach 2:
The patent segments the hydrocarbon separation process into distinct functional stages: membrane-based concentration, cooling, compression, and final separation. This modular segmentation allows each component to be optimized independently and simplifies the overall system design compared to a monolithic cryogenic system.
3Loss of substance
If process gas is cooled for hydrocarbon liquefaction, then hydrocarbon separation is improved, but water icing risk increases
Solution Approach 1:
The patent performs preliminary dehumidification of the process gas before the cooling and hydrocarbon separation steps. By removing water content in advance, the subsequent cooling to non-cryogenic temperatures does not result in water icing, thus protecting system components while maintaining hydrocarbon separation efficiency.
Solution Approach 2:
The patent changes the temperature parameter to non-cryogenic ranges (above 0°C) for the hydrocarbon liquefaction step. This parameter change, combined with preliminary dehumidification, ensures that water remains in liquid form rather than freezing, eliminating the water icing risk while still achieving effective hydrocarbon separation through the membrane concentration and cooling process.
4Quantity of substance
If membrane separation is used to concentrate hydrocarbons, then hydrocarbon content in process gas is improved, but additional equipment is required
Solution Approach 1:
The patent introduces a membrane device as an intermediary component that selectively concentrates hydrocarbons from the process gas. This intermediary step creates a hydrocarbon-enriched gas stream that is then easier to separate in subsequent cooling and compression stages, achieving the benefit of enhanced hydrocarbon content while using a relatively simple membrane module.
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 system effectively recovers hydrocarbons without cryogenic cooling, reducing energy consumption and complexity, minimizing water icing risks, and ensuring safe operation by controlling oxygen content, thus achieving efficient and cost-effective recycling.
Implementation Method 1
cool the process gas to a dehumidification temperature, optionally in the range of 5°–20°C, so that water is separated from the process gas via condensation
Implementation Method 2
cool the compressed process gas to a separation operating temperature in the range of 5-15°C in order to separate the hydrocarbon contained in the process gas as liquid hydrocarbon via condensation
Implementation Method 3
a membrane device which is connected to the gas-liquid separator via a process gas return line to obtain the remaining process gas, which is configured such that a hydrocarbon-enriched return process gas is obtained from the remaining process gas on a permeate side of the membrane device
Data Source
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AI summary
Refrigerator recycling plant (1) and method (S300) for recycling refrigerators (22), wherein the refrigerator recycling plant (1) comprises: a refrigerator shredding device (10), an inert gas source (30), a dehumidification cooling device (40), a process gas line (50), a compressor (60), a cooling device (70), a gas-liquid separation device (80), a process gas return line (100), a membrane device (90), and a pressure swing adsorption device (200), wherein the membrane device (90) is configured such that a hydrocarbon-enriched recycle process gas is obtained from the remaining process gas on a permeate side (92) of the membrane device (90) and a hydrocarbon-poor further process gas is obtained on a retentate side (94) of the membrane device (90).wherein the permeate side (92) thereof is connected via a hydrocarbon-enriched gas return line (110) to the process gas line (50) at a return point (112) upstream of the compressor (60), optionally between the dehumidification-cooling device (40) and the compressor (60), in order to return the hydrocarbon-enriched return process gas to the process gas at this return point (112), and wherein the retentate side (94) thereof is connected to a hydrocarbon-lean gas forward line (120) in order to forward the hydrocarbon-lean forward process gas.