Entrained Flow Gasification of Plastics and Fossil Fuels
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Solution Overview
Problem
Current waste gasification technologies face challenges in producing a syngas stream suitable for chemical synthesis due to variability in syngas composition, high tar production, and instability of plastic-based feedstocks in gasifiers, leading to inefficient and costly purification processes.
Innovation Solution
An entrained flow gasification process is employed, using a feedstock composition with up to 25% plastics and a solid fossil fuel, where the plastics are pre-ground to less than 2 mm and the slurry is stabilized to ensure pumpability and minimal tar yield, resulting in a syngas stream with reduced variability and suitability for chemical production without the need for extensive purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If air supplied fluidized bed gasifiers are used for waste gasification, then the gasifier can accept a variety of component sizes and types, but incomplete oxidation reactions occur resulting in high quantities of residues and widely variable syngas compositions
Solution Approach 1:
The patent changes the operating temperature parameter from low to medium (500-1000°C) to high temperature (above 1000°C), which fundamentally alters the oxidation completeness and syngas composition stability. This temperature parameter change resolves the contradiction by enabling consistent syngas production while maintaining feedstock versatility.
Solution Approach 2:
The patent uses a composite feedstock composition comprising both plastics (up to 25 wt.%) and solid fossil fuels (at least 75 wt.%). This composite approach leverages the advantages of both materials: plastics provide high heat value while fossil fuels provide stable carbon content and consistent gasification characteristics, resulting in reliable syngas composition.
2Use of energy by moving object
If plastics are used as feedstock in gasifiers, then high heat value is achieved, but syngas composition variability increases due to mixed plastic polymer structures
Solution Approach 1:
The patent changes the particle size parameter of plastics to less than 2 mm through pre-grinding. This parameter change ensures uniform heat release and consistent gasification behavior, resolving the composition stability issue while preserving the high heat value advantage of plastics.
Solution Approach 2:
The patent creates a composite feedstock system where plastics (providing high heat value) are combined with solid fossil fuels (providing composition stability). The fossil fuel component acts as a stabilizing matrix that dampens the variability inherent in mixed plastic feedstocks, delivering consistent syngas composition.
3Object-generated harmful factors
If high temperature gasification is employed to reduce tar production, then oxidation completeness improves, but energy consumption increases
Solution Approach 1:
The patent implements a self-sustaining high temperature gasification process where the combination of plastics and fossil fuels provides sufficient heat value to maintain temperatures above 1000°C without external energy input. The system uses its own feedstock energy content to achieve the high temperatures needed for complete oxidation and minimal tar production.
Solution Approach 2:
The composite feedstock of plastics and fossil fuels provides a synergistic energy contribution that sustains high temperature operation. The fossil fuels contribute stable combustion characteristics that maintain temperature consistency, reducing the need for additional energy input while ensuring complete oxidation and low tar yield.
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 process achieves a stable and consistent syngas composition, reducing tar production and operational costs by maintaining syngas quality over time, enabling efficient chemical synthesis without the need for additional purification steps beyond acid gas removal.
Implementation Method 1
gasifying the feedstock composition together with the oxidant in a gasification zone to produce a syngas composition
Implementation Method 2
gasification of such waste stocks... using air as an oxidizer... incomplete oxidation reactions occur
Implementation Method 3
incomplete oxidation reactions occur resulting the generating of high quantities of residues that can appear in both the gas phase (syngas stream) and bottoms solid phase
Data Source
AI summary
Pre-ground plastics of small particle size not more than 2 mm are co-fed into a solid fossil fuel fed entrained flow partial oxidation gasifier. High solids concentrations in the feedstock stream can be obtained without significant impact on the feedstock stream stability and pumpability. A consistent quality of syngas can be continuously produced, including generation of carbon dioxide and a carbon monoxide/hydrogen ratio while stably operating the gasifier and avoiding the high tar generation of fluidized bed or fixed bed waste gasifiers and without impacting the operations of the gasifier. The subsequent syngas produced from this material can be used to produce a wide range of chemicals.