Secondary Solid Fuel Production via Density-Based NIR Separation
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Solution Overview
Problem
Existing methods for producing secondary solid fuel (SSF) face inefficiencies due to the limited flow rates of NIR optical separators, which are necessary for removing chlorinated plastics, leading to slowed processes and increased costs when trying to handle higher flow rates in waste treatment plants.
Innovation Solution
The method and plant design selectively subject only intermediate density waste to NIR optical separators for chlorinated plastic separation, while separating fine and heavy waste separately, and mixing light and intermediate waste post-processing, thereby optimizing the refining step to handle higher flow rates efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NIR optical separators are used to remove chlorinated plastics from all waste fractions, then the removal efficiency of chlorinated plastics is improved, but the process flow rate decreases significantly
Solution Approach 1:
The waste stream is segmented into different density fractions (light, intermediate, heavy) using gravimetric separation. The NIR optical separator is then applied only to the intermediate density fraction where chlorinated plastics are most concentrated, rather than treating the entire waste stream. This segmentation allows the limited-capacity NIR separator to handle the critical fraction efficiently while maintaining high overall process flow rate.
Solution Approach 2:
The separation process applies different treatment qualities to different waste fractions based on their specific characteristics. The intermediate density fraction receives intensive NIR optical separation because it contains the highest concentration of chlorinated plastics, while light and heavy fractions receive different or no treatment. This local quality approach optimizes resource allocation and maintains process efficiency.
2Productivity
If multiple NIR optical separators are introduced in parallel to increase flow rate capacity, then the process flow rate is improved, but the device complexity and manufacturing costs increase
Solution Approach 1:
The problematic chlorinated plastics are extracted from the waste stream before reaching the NIR optical separator through preliminary gravimetric separation. By removing light and heavy fractions first, only the intermediate fraction containing chlorinated plastics is fed to the NIR separator. This extraction approach allows a single NIR separator to handle the entire chlorinated plastic removal task efficiently, avoiding the need for multiple parallel separators.
3Reliability
If all waste fractions are subjected to chlorinated plastic separation, then the purity of SSF is improved, but the loss of time and process efficiency increase
Solution Approach 1:
Gravimetric separation is performed as a preliminary action before the NIR optical separation step. This preliminary separation concentrates the chlorinated plastics into the intermediate density fraction, so that the subsequent NIR separation step only needs to process a smaller, targeted stream. This preliminary action significantly reduces the time required for the main separation operation while ensuring high purity of the final SSF product.
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 the efficiency of SSF production by focusing separation efforts on intermediate density waste, reducing the need for multiple NIR separators and minimizing process slowdowns, while ensuring the removal of chlorinated plastics and metals, resulting in a more homogeneous and efficient fuel production process.
Implementation Method 1
use of optical separators using NIR (Near Infra-Red) technology
Data Source
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Figure 1b
Figure 2a
AI summary
The present invention relates to a method and a plant for producing secondary solid fuel (SSF). The invention provides for removing fine and heavy waste from the flow of treated waste and further subdividing the remaining waste into intermediate waste and light waste (137). According to the invention, only the fraction of intermediate waste is subjected to the removal of chlorinated plastics (PVC). Advantageously, thanks to the fact that only a small fraction of the treated waste is subjected to said removal of the chlorinated plastics (134), the invention allows to obtain high efficiency in the treatment of waste and in the production of SSF. In a preferred embodiment of the invention, said intermediate waste fraction is also subjected to the removal of ferrous metals and non-ferrous metals (aluminum) (135).