Coal Drying Using Waste Heat and Fluidized Bed Technology
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Solution Overview
Problem
Existing coal drying processes in power plants are inefficient and costly due to the reliance on high temperatures and fossil fuels, which increases energy consumption and emissions, and do not effectively utilize waste heat sources for drying low-rank coals like subbituminous and lignite, limiting their viability as fuel sources.
Innovation Solution
The use of waste heat sources, such as hot flue gas and condenser cooling water, in a low-temperature, open-air process to dry coal, reducing moisture content and enhancing boiler efficiency without the need for additional fossil fuel combustion, utilizing fixed and fluidized bed dryers to pre-dry and clean the coal before combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperatures and fossil fuels are used for coal drying, then drying effectiveness is improved, but energy consumption and emissions increase
Solution Approach 1:
The invention converts waste heat from flue gas and condenser cooling water, which would otherwise be discarded, into a useful drying medium for low-rank coals. This transforms harmful waste thermal energy into a beneficial resource that reduces moisture content in coal without requiring additional fossil fuel combustion, thereby resolving the contradiction between drying effectiveness and energy consumption
Solution Approach 2:
The invention changes the temperature parameter of the drying process by using waste heat sources that operate at lower temperatures compared to conventional high-temperature drying methods. This parameter change allows effective drying of low-rank coals while significantly reducing energy consumption and avoiding the need for additional fossil fuel combustion
2Manufacturing precision
If high temperatures and fossil fuels are used for coal drying, then drying effectiveness is improved, but emissions increase
Solution Approach 1:
The invention converts waste heat from flue gas and condenser cooling water, which would otherwise be discarded, into a useful drying medium for low-rank coals. This transforms harmful waste thermal energy into a beneficial resource that reduces moisture content in coal without requiring additional fossil fuel combustion, thereby resolving the contradiction between drying effectiveness and energy consumption
Solution Approach 2:
The system uses its own waste heat outputs (flue gas and condenser cooling water) to perform the drying function, making the plant self-sufficient for this auxiliary process. This eliminates the need for external fossil fuel combustion dedicated to drying operations, thereby reducing emissions while maintaining drying effectiveness
3Use of energy by moving object
If waste heat sources are used for drying low-rank coals, then energy consumption is reduced, but drying effectiveness may be compromised
Solution Approach 1:
The invention makes waste heat sources serve multiple functions: flue gas is used both for its thermal energy to heat drying media and potentially for direct drying, while condenser cooling water provides additional thermal energy. This multi-functional use of waste heat ensures sufficient drying effectiveness is achieved while minimizing energy consumption
Solution Approach 2:
The drying system uses a composite approach by combining multiple waste heat sources (flue gas and condenser cooling water) to create a combined heating system. This composite thermal system provides sufficient total heat input to achieve effective drying of low-rank coals while maintaining low energy consumption
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 approach significantly reduces the moisture content of coal, improves boiler efficiency, decreases emissions, and makes low-rank coals more economically viable by utilizing waste heat, thereby enhancing the operational efficiency and environmental impact of power plants.
Implementation Method 1
The use of waste heat sources, such as hot flue gas and condenser cooling water, in a low-temperature, open-air process to dry coal
Implementation Method 2
to dry coal, reducing moisture content and enhancing boiler efficiency
Data Source
AI summary
The present invention harvests and utilizes fluidized bed drying technology and waste heat streams augmented by other available heat sources to dry feedstock or fuel. This method is useful in many industries, including coal-fired power plants. Coal is dried using the present invention before it goes to coal pulverizers and on to the furnace/boiler arrangement. Coal can be intercepted on current coal feed systems ahead of the pulverizers. Drying fuel, such as coal, is done to improve boiler efficiency and reduce emissions. A two-stage bed utilized in the process first “pre-dries and separates” the feed stream into desirable and undesirable feedstock. Then, it incrementally dries and segregates fluidizable and non-fluidizable material from the product stream. This is all completed in a low-temperature, open-air system. Elevation of fan room air temperature is also accomplished using waste heat, thereby making available to the plant system higher temperature media to enhance the feedstock drying process.