Two-Stage Gasification Combustion System for MSW
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Solution Overview
Problem
Conventional combustion systems for municipal solid waste (MSW) produce undesirable emissions such as Nitrous Oxides (NOx), carbon monoxide, and dioxins, and lack efficiency in converting MSW to energy while minimizing harmful emissions.
Innovation Solution
A gasification combustion system that controls oxidant supply and temperature, using a moving grate, primary and secondary air sources, and post-combustion controls like selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) to minimize NOx formation and emissions, with a two-stage refuse gasification system for complete combustion and energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional combustion is used to dispose of MSW, then energy recovery is achieved, but harmful emissions such as NOx, carbon monoxide, and dioxins are produced
Solution Approach 1:
The combustion process is divided into two distinct stages: a first combustion chamber where MSW is combusted at controlled conditions to produce syngas, and a second combustion chamber where syngas is combusted. This segmentation allows each stage to be optimized for specific functions, reducing harmful emissions while maintaining energy recovery efficiency
Solution Approach 2:
The system changes the parameters of combustion by controlling oxygen supply and temperature in the first combustion chamber to produce syngas with higher heating value, rather than complete combustion. This parameter change reduces the formation of NOx and other harmful emissions while still achieving energy recovery
2Reliability
If high oxygen supply is used in combustion, then complete combustion is achieved, but thermal NOx formation increases due to high temperatures
Solution Approach 1:
The combustion process is segmented into two stages: first stage with controlled oxygen supply to avoid thermal NOx formation, and second stage where syngas is combusted. This segmentation allows complete combustion to be achieved without subjecting atmospheric nitrogen to high temperatures that would cause thermal NOx
Solution Approach 2:
The system performs preliminary combustion of MSW in the first chamber to produce syngas before the second combustion stage. This preliminary action converts the fuel into a more efficient form while controlling the combustion conditions to minimize harmful emissions
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 with reduced harmful emissions, increased heating value of syngas, and minimized NOx and CO levels in flue gas, enhancing energy integration and waste processing efficiency.
Implementation Method 1
a moving grate that enables the movement of waste through the combustion chamber
Implementation Method 2
Primary air may be supplied from under the grate and forced through the grate to sequentially dry (evolve water), de-volatilize (evolve volatile hydrocarbons), and burn out (oxidize nonvolatile hydrocarbons) along the waste bed
Implementation Method 3
Secondary air may be supplied through nozzles located above the grate and used to create turbulent mixing that destroys the hydrocarbons that evolved from the waste bed
Implementation Method 4
By controlling the oxidant supply and temperature of gasification or combustion, the system can more efficiently burn refuse and reduce the emission of harmful products
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 gas regulator, and a post combustor. Additionally, methods for regulating gas and advancing refuse through a two stage refuse gasification combustion system are disclosed.