Molten Salt Heat Transfer for Biomass Drying
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Solution Overview
Problem
Existing energy generation plants using combustion boilers for biomass are costly due to stringent material requirements for corrosion resistance and pressure handling, leading to high maintenance and operational expenses, especially when dealing with aggressive sediments and high pressures.
Innovation Solution
The energy generation plant employs a heat exchange system using molten salt or molten metal heated to beyond 350 °C, which is used in an overheated-steam drier to dry wet biomass efficiently, eliminating the need for pressurized systems and allowing the use of less expensive, corrosion-resistant materials for the boiler wall, and incorporates a circulating fluidized bed boiler for better temperature control and energy recovery systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a combustion boiler with pressurized water system is used, then high efficiency energy generation is achieved, but the boiler wall requires expensive corrosion-resistant materials and high pressure handling capabilities
Solution Approach 1:
The patent introduces molten salt as an intermediary heat transfer medium between the combustion chamber and the drying system. The molten salt absorbs heat from combustion gases and transports it to dry biomass, eliminating the need for pressurized water systems and expensive corrosion-resistant boiler walls while maintaining high thermal efficiency
Solution Approach 2:
The patent changes the physical state and operating parameters of the heat transfer medium from pressurized liquid water to molten salt operating at atmospheric pressure. This parameter change allows the system to achieve high temperatures (above 350°C) without requiring high pressure containment, thus reducing material costs
2Object-affected harmful factors
If a combustion boiler with thick brick or concrete walls is used, then resistance to aggressive sediments is improved, but the system cannot resist high pressures at small thickness and requires regular maintenance
Solution Approach 1:
The molten salt acts as a mediator that transfers heat without requiring direct contact between combustion gases and the drying system. This eliminates sediment deposition and chemical corrosion issues while maintaining effective heat transfer
Solution Approach 2:
The patent uses a simpler, less expensive heat exchange system that operates at atmospheric pressure with molten salt, eliminating the need for thick, expensive, maintenance-intensive brick or concrete boiler walls
3Productivity
If molten salt or molten metal is used as heat transfer medium heated to beyond 350 °C, then drying efficiency of wet biomass is improved, but the system complexity increases
Solution Approach 1:
The patent utilizes the phase transition properties of molten salt, which remains in liquid state at operating temperatures above 350°C, enabling efficient heat transfer. The molten salt can be heated to high temperatures without pressurization, simplifying the system while improving drying efficiency
Solution Approach 2:
The molten salt system operates at atmospheric pressure without requiring complex pressure containment systems, safety valves, or specialized high-pressure components, thereby reducing system complexity despite the high operating temperature
4Temperature
If pressurized water system is used in combustion boiler, then high temperature heat transfer is achieved, but inspection costs and manufacturing costs increase due to safety requirements
Solution Approach 1:
The patent changes the operating pressure parameter from high pressure to atmospheric pressure while using molten salt to achieve the required high temperatures. This parameter change eliminates the need for expensive pressure-containing systems and reduces inspection costs
Solution Approach 2:
Molten salt serves as an intermediary that enables high-temperature heat transfer at atmospheric pressure, eliminating the need for pressurized systems and associated safety infrastructure, thereby reducing manufacturing and inspection costs
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 reduces inspection and manufacturing costs, enhances efficiency, and provides a safer, more cost-effective energy generation process with improved biomass drying efficiency and reduced environmental risks from leaks, while maintaining high-temperature energy transfer capabilities.
Implementation Method 1
a heat exchange system which heats a heat transfer medium by the heat produced during the thermal conversion and transports this heat transfer medium to the drying system where the heat in the heat transfer medium is utilized for the drying process
Implementation Method 2
the steam needed for drying the biomass is heated by the heat transfer medium to a temperature exceeding 150 °C
Implementation Method 3
an overheated-steam drier in which overheated steam comes into contact with the wet biomass to be dried
Implementation Method 4
molten salt or molten metal is not under pressure, it is not necessary to comply with the inspection demands for pressurized systems. This reduces the inspection costs as a result of which the cost of design and manufacturing of the energy generation plant may be maintained at a low level
Data Source
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AI summary
An energy generation plant 1 comprises a drying system 3 for drying wet biomass 4, as well as a thermal conversion system 5 for generating energy from dried biomass 6, and a heat exchange system 7 which heats a heat transfer medium 9 by the heat produced during the thermal conversion and feeds this heat transfer medium to the drying system where the heat in the heat transfer medium is utilized for the drying process. Molten salt or molten metal is used here as a heat transfer medium. The drying system 3 is arranged as an overheated- steam drier 23 wherein steam needed for drying the wet biomass is heated by the heat transfer medium 9. An energy recovery system 21 provides the recovery of energy from the water vapour that has arisen from the drying process. The thermal conversion system is formed by a combustion boiler 13 having a boiler wall 15 and a combustion space 17 found inside. The bottom of the combustion boiler is formed by a fluidized bed combustor 19.