Solid Fuel Drying via Heat Recovery and Inert Gas Circulation
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Solution Overview
Problem
Existing methods for drying water-containing solid fuels, such as biomass, often require large heat sources like boilers and suffer from inefficiencies in energy consumption due to inadequate utilization of sensible and latent heat.
Innovation Solution
A drying apparatus and method utilizing a circulation system with a heat transfer pipe, dust collector, compressor, heat exchanger, and gas-liquid separating device to effectively utilize sensible and latent heat from a mixed gaseous fluid, reducing the need for large-scale heat sources and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If combustion exhaust gas is used as a drying heat source, then drying can be performed, but a boiler must be installed and latent heat is not recovered causing large heat loss
Solution Approach 1:
The patent utilizes phase transitions of water (evaporation and condensation) to transfer latent heat. Water evaporates from the solid fuel surface absorbing latent heat, then the vapor condenses on heat exchange surfaces releasing latent heat to preheat incoming air. This phase transition-based heat recovery system eliminates the need for a boiler and reduces energy loss by capturing otherwise wasted latent heat from exhaust gases.
Solution Approach 2:
The system changes the temperature and pressure parameters of the drying gas through multiple heat exchange stages. Incoming air is preheated by condensing vapor, then further heated by sensible heat transfer from hot dry air. The drying gas temperature and humidity parameters are continuously adjusted through these thermal processes, enabling efficient drying without requiring a boiler to generate high-temperature exhaust gases.
2Productivity
If air is injected during through-flow drying, then drying speed increases, but ignition risk occurs for flammable raw materials
Solution Approach 1:
The patent uses inert gas (nitrogen or carbon dioxide) as an intermediary medium instead of air for through-flow drying. These inert gases do not support combustion, eliminating ignition risk for flammable materials like biomass. The inert gas circulates through the material bed, providing oxygen-free drying while maintaining the productivity benefits of through-flow drying methodology.
3Loss of energy
If sensible heat of drain is not utilized, then system is simple, but large heat loss occurs via externally exhausted heat
Solution Approach 1:
The patent merges the drain stream with the incoming air stream in a heat exchanger. The hot drain gas, which contains both sensible heat and latent heat from evaporated moisture, is combined with the incoming fresh air. This merging allows heat transfer from the drain to preheat the incoming air, recovering both sensible and latent heat that would otherwise be lost through external exhaust, thereby reducing overall 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
The system efficiently dries water-containing solid fuels with low energy consumption, eliminating the need for large equipment like boilers and allowing for a compact, cost-effective drying process while lowering the drying temperature by adjusting the vapor's boiling point.
Implementation Method 1
a heat exchanger that preheats low-pressure mixed gaseous fluid introduced into the compressor from the dust collector with high-pressure mixed-gaseous fluid that has been compressed at the compressor
Implementation Method 2
the water-containing solid fuel is dried by heating the water-containing solid fuel with latent heat of vapor contained in the mixed gaseous fluid and sensible heat of the mixed gaseous fluid
Implementation Method 3
introducing water-containing scavenging gas which flows out from the heat transfer pipe while containing moisture formed through condensing of vapor contained in the gas
Data Source
AI summary
A water-containing solid fuel drying apparatus that can efficiently dry with low energy consumption by effectively utilizing sensible heat and latent heat of a heating medium for drying, etc. is provided. A drying apparatus (10) that dries water-containing solid fuel includes a dryer (20) that injects scavenging gas into the interior of a drying vessel (21) in which a heat transfer pipe (22) is disposed; a dust collector (13) that removes microparticles from microparticle-containing mixed gaseous fluid that has flowed out of the drying vessel (21); a compressor (30) that compresses vapor-containing mixed gaseous fluid; a vapor heat exchanger (31) that preheats low-pressure mixed gaseous fluid with high-pressure mixed gaseous fluid compressed at the compressor (30); and a gas-liquid separator (14), in which the high-pressure mixed gaseous fluid is employed as drying gas that radiates heat by passing through the heat transfer pipe (22), that performs gas-liquid separation of water-containing scavenging gas that has flowed out of the heat transfer pipe (22) while containing condensed water of vapor generated due to heat radiation, wherein the water-containing solid fuel is dried by heating the water-containing solid fuel in the drying vessel (21) utilizing latent heat and sensible heat of the mixed gaseous fluid.