Two-Stage Gasification Combustion System for MSW
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Solution Overview
Problem
Conventional combustion systems for municipal solid waste (MSW) face challenges such as the production of undesirable emissions like NOx and carbon monoxide, and difficulties in handling high moisture content refuse, which leads to unstable combustion and reduced efficiency.
Innovation Solution
A gasification combustion system that controls oxidant supply and temperature, utilizing a moving grate, primary and secondary air sources, and post-combustion controls like SNCR and SCR systems, along with a two-stage gasification process to efficiently burn refuse and minimize harmful emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional combustion is used to dispose of MSW, then energy recovery is achieved, but harmful emissions (NOx, carbon monoxide, dioxins) are produced
Solution Approach 1:
The combustion process is divided into two distinct stages: gasification in the first gasifier and combustion in the second gasifier. This segmentation allows the fuel-bound nitrogen to be converted to ammonia in the reducing environment of the first gasifier, which then combusts cleanly in the second stage, significantly reducing NOx emissions while maintaining energy recovery
Solution Approach 2:
The system changes the oxygen concentration parameter from conventional high-oxygen combustion to controlled low-oxygen gasification in the first gasifier (30-65% oxygen concentration), then introduces secondary air in the second gasifier for complete combustion. This parameter change transforms the chemical reactions to minimize harmful emissions while recovering energy
2Productivity
If high moisture content refuse is combusted, then waste disposal is achieved, but combustion stability decreases and furnace temperature drops
Solution Approach 1:
The first gasifier performs preliminary gasification of the refuse before combustion in the second gasifier. This preliminary action converts the fuel and removes moisture in a controlled reducing environment, preventing the temperature drops and instability that would occur if high moisture refuse were directly combusted
Solution Approach 2:
The first gasifier acts as an intermediary between the raw high moisture refuse and the combustion process in the second gasifier. It pre-processes the fuel through gasification, creating a more stable fuel source for combustion and isolating the moisture issue from the combustion chamber
3Temperature
If high gas flow is used to dry high moisture refuse, then drying is achieved, but fan power requirements increase and boiler efficiency decreases
Solution Approach 1:
The system changes the oxygen concentration parameter to 30-65% in the first gasifier, creating a controlled gasification environment that efficiently dries and gasifies the refuse without requiring excessive air flow. This parameter change enables effective drying at lower fan power requirements compared to conventional air drying
Solution Approach 2:
The use of controlled oxygen-enriched gas (30-65% oxygen concentration) in the first gasifier accelerates the gasification and drying process, achieving effective moisture removal and fuel conversion more efficiently than conventional air flow methods, thereby reducing fan power requirements
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 achieves efficient energy conversion, reduces harmful emissions, and effectively handles high moisture content refuse by optimizing air flow and temperature control, resulting in a more durable and efficient combustion process.
Implementation Method 1
a first gasifier for processing the refuse to produce a first combustible gas
Implementation Method 2
a combustor for burning the combustible gas
Implementation Method 3
SNCR systems and SCR systems
Implementation Method 4
SNCR systems and SCR systems
Data Source
AI summary
A two stage refuse gasification combustion system for processing refuse is disclosed. The system may contain features such as an advancer, a first and second gasifier, a drier, a gas regulator, and a post combustor. Additionally, methods for regulating gas and advancing refuse through a two stage refuse gasification combustion system are disclosed.