Three-Stage Gasification for Low-Density Carbon Feedstock
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Solution Overview
Problem
Existing methods face challenges in efficiently utilizing carbon-containing feedstocks for gasification due to their low energy density, fibrous structure, and operational issues with dust formation, necessitating a more effective and efficient gasification process.
Innovation Solution
A three-stage gasification method involving pre-gasification (pyrolysis), followed by separate processing of pyrolysis vapors and solid products, using granulated pyrolysis coke in a stationary bed gasifier, with waste heat recovery for steam generation and pyrolysis preheating, and subsequent cooling and filtration to produce high-quality syngas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If solid biogenic fuels with low compressed bale density are used in gasification, then the process can handle diverse feedstock, but the energy density is low and processing efficiency is poor
Solution Approach 1:
The gasification process is divided into three distinct stages: pre-gasification (pyrolysis) to decompose feedstock into vapor-gas mixture and solid residue, gasification of pyrolysis vapors to produce syngas, and gasification of solid fuels in a stationary bed. This segmentation allows each stage to be optimized independently, enabling the system to handle diverse low-density feedstock while maintaining high energy conversion efficiency through specialized processing for each material type.
2Device complexity
If traditional gasification methods are used, then the process is simpler, but dust formation and operational issues increase
Solution Approach 1:
A pre-gasification (pyrolysis) stage is implemented before the main gasification process. This preliminary action decomposes the feedstock into vapor-gas mixture and solid residue, preventing dust formation during subsequent processing. The pyrolysis step converts fibrous and particulate matter into gaseous products that can be efficiently gasified without generating operational dust issues, while the solid residue is separately processed in the stationary bed.
3Productivity
If pyrolysis vapor and solid products are processed separately, then processing efficiency improves, but system complexity increases
Solution Approach 1:
The system processes pyrolysis vapors and solid products through separate but integrated pathways: vapors are directed to a gasification reactor for syngas production, while solid residue is fed to a stationary bed gasifier. This segmentation improves processing efficiency by optimizing conditions for each material type independently, while the integrated design shares common infrastructure (feedstock preparation, heat recovery systems, syngas collection) to limit overall system complexity.
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 method enables the efficient conversion of diverse carbon-containing feedstocks into high-quality syngas, suitable for various applications, by overcoming structural and operational limitations of previous methods, and facilitating the production of energy-rich syngas.
Implementation Method 1
Fast pyrolysis of the pre-dried and optionally ground feedstock
Implementation Method 2
a compression system coupled in flow communication between the pyrolysis unit and the slurry preparation unit, used to condense the pyrolysis gas into a liquid
Implementation Method 3
a cooler used to receive and cool said syngas steam
Implementation Method 4
Gasification takes place in an entrained-flow gasifier at temperatures below 1200°C and increased pressure up to 120 bar
Data Source
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AI summary
The present invention relates to a method of generating a producer gas (Synthesis gas - syngas) from carbon contained feedstock. The method is a three-stage gasification, including pre-gasification - pyrolysis; gasification of pyrolysis vapor-gas mixture; gasification of solid fuels. As feedstock can be used any carbon contained feedstock like Refuse Derived Fuel (RDF), medical waste, agricultural waste, tires, automobile shredder residue (ASR or car-fluff), residues and waste materials, biomass such as straw, wood or grass, but also from the biogenic solid or liquid waste resulting from the food industry, sewage sludge from waste water treatment, spent high-salt solutions from wood pulping, known as black liquor, and products from animal carcass processing, such as animal meal. Method for three-stage gasification from carbon contained feedstock, including gasification processes preceded by reduction of water content, pre-gasification - pyrolysis of the pre-dried and optionally ground feedstock, at a pressure that is lower or higher than atmospheric; after the gasification process, the gas is cooled; the process of pre-gasification - pyrolysis takes place at temperatures between 240 and 900 °C, at a pressure that is lower or higher than atmospheric; gasification processes take place at temperatures between 800 and 2200 °C, at pressures that are lower or higher than atmospheric; the required amount of oxygen for the gasification process is introduced by adding air or mixture pure oxygen and water vapor and/or other inert component in gas form, like CO2 etc.; the gasification fluid from the gasification stage can be used alone or in combination with other gases, as a heater - heating agent in the preceding pre-gasification stage - pyrolysis; the waste heat from the gasification processes can be used to generate low or highpressure and/or preheated steam and/or for preheating the air needed for gasification, and/or for heat recuperation for pyrolysis agent, in several steps of agent preheating; the products from pre-gasification - pyrolysis: a vapor-gas mixture and a solid phase - charcoal or coke can be used alone or in combination as a fuel in the gasification stage; granulation of pyrolysis solid product - coke or charcoal, alone or whit some additives like heavy tars from gasification and/or with small fraction of feeding materials, with low temperature melting point like small plastic particles etc.; direct continuous or periodic gasification of pyrolysis vapors with air or air/steam or oxygen/steam or oxygen/CO2 in the burner on gasifier; direct continuous or periodic gasification of carbon granules with air or air/steam or oxygen/steam or oxygen/Co2 in the stationary bed in gasifier; all gases from pyrolysis vapor gasification or pyrolysis vapors itself pass through heated to high temperatures carbon granules, located on stationary bed of gasifier