Fuel Preprocess System for Coal Boiler Using Flue Gas and Primary Air
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Solution Overview
Problem
Conventional coal combustion boilers face inefficiencies when burning biomass or refuse-derived fuel due to low reaction temperatures and the need for significant modifications to fuel supply equipment, which affects stability and boiler efficiency.
Innovation Solution
A fuel preprocess system that uses primary air or flue gas from a coal combustion boiler to dry and devolatilize biomass or refuse-derived fuel, reusing the primary air as combustion air and discharging the flue gas used for drying, thereby enhancing boiler efficiency without altering the boiler's heat distribution load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If biomass or refuse-derived fuel is burned in a conventional coal combustion boiler without replacing the pulverizer or burner, then the existing boiler infrastructure is preserved, but the fuel supply equipment needs drastic modification and the pulverizer needs to be overdriven, lowering facility stability
Solution Approach 1:
The patent applies preliminary action by implementing a preprocessing system that dries and torrefies biomass fuel before it enters the boiler. This pre-treatment prepares the fuel in advance to match the requirements of the existing coal combustion system, allowing the pulverizer and burner to operate within their designed parameters without overdriving, thus maintaining facility stability while preserving infrastructure
Solution Approach 2:
The patent changes physical parameters of the biomass fuel through drying (reducing moisture content) and torrefaction (thermal treatment at controlled temperatures). These parameter changes transform the fuel properties to be compatible with conventional coal combustion systems, enabling the existing infrastructure to process alternative fuels without modification while maintaining operational stability
2Adaptability or versatility
If a new pulverizer is applied for biomass and refuse-derived fuel, then the fuel can be processed, but a preprocess such as drying is needed when the fuel contains large amounts of hemi-cellulose or moisture, making it difficult to apply the conventional system
Solution Approach 1:
The patent implements preliminary drying and torrefaction processes that prepare biomass fuel before it enters the pulverizer. By removing moisture and performing thermal pretreatment in advance, the system eliminates the need for complex preprocessing equipment while maintaining the ability to handle high-moisture, high-hemi-cellulose fuels effectively
Solution Approach 2:
The patent employs self-service principles by using the boiler's own flue gas for drying and its own primary air for torrefiction. This internal resource utilization eliminates the need for external preprocessing systems, reducing device complexity while maintaining fuel processing versatility
3Use of energy by moving object
If flue gas is used for drying biomass fuel, then energy utilization is improved, but the flue gas temperature decreases
Solution Approach 1:
The patent converts the harmful waste heat in flue gas into a beneficial drying medium. By directing flue gas through the biomass fuel in the drying chamber, the system utilizes the otherwise wasted thermal energy to evaporate moisture, thereby improving overall energy utilization efficiency while the temperature decrease is acceptable since the flue gas is being discharged anyway
4Productivity
If primary air is used for torrefiction, then the drying process is enhanced, but the primary air temperature decreases
Solution Approach 1:
The patent converts the primary air after it has served its combustion function into a beneficial torrefiction medium. By directing this cooled primary air through the dried biomass in the torrefiction chamber, the system utilizes the residual heat to perform thermal pretreatment, enhancing productivity while the temperature decrease is acceptable since the air is being discharged or recirculated anyway
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 improves boiler efficiency by utilizing the heat from flue gas for drying and primary air for torrefaction, reducing energy losses and increasing the efficiency of fuel combustion, allowing for the effective use of biomass or refuse-derived fuel without compromising the existing boiler infrastructure.
Implementation Method 1
a dryer configured to dry the biomass or refuse-derived fuel by use of flue gas generated after combustion in the boiler
Implementation Method 2
drying the biomass or refuse-derived fuel by use of flue gas
Implementation Method 3
a torrefier configured to devolatilize a fibrous component contained in the dried fuel from the fuel dried in the dryer by use of primary air that is heat-exchanged after the combustion in the boiler
Data Source
AI summary
A fuel preprocess system for a coal combustion boiler is disclosed. The fuel preprocess system for a coal combustion boiler that dries biomass or refuse-derived fuel in accordance with the present invention can include: a dryer configured to dry the biomass or refuse-derived fuel by use of flue gas generated after combustion in the boiler; and a torrefier configured to devolatilize a fibrous component contained in the dried fuel from the fuel dried in the dryer by use of primary air that is heat-exchanged after the combustion in the boiler.