Grain Tower Dryer Counter-Flow Cooling and Heat Reclamation
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Solution Overview
Problem
Current grain tower dryers cause damage to grain due to rapid cooling, leading to breakage and increased fine material, and inefficiencies in heat reclamation, which affects grain quality and processing efficiency.
Innovation Solution
A tower dryer design incorporating a counter-flow cooling section with non-porous walls and strategically placed ducts to slow down the cooling process, combined with a heat reclamation system that recycles warm exhaust air to reduce energy consumption and minimize temperature differentials, using a blower to create negative pressure in the cooling plenum and draw in ambient air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cross-flow cooling is used to cool the grain rapidly, then cooling efficiency is improved, but grain breakage increases
Solution Approach 1:
The patent inverts the conventional cross-flow cooling approach by implementing counter-flow cooling, where cooling air moves in the opposite direction to grain flow. This reversal allows the coldest air to contact the coolest grain at the bottom while warmer air contacts hotter grain at the top, eliminating rapid temperature differentials that cause grain breakage while maintaining effective cooling.
Solution Approach 2:
The patent changes the temperature parameter distribution along the cooling path by using counter-flow arrangement. Instead of uniform or cross-flow temperature contact, the system creates a gradient where temperature difference between air and grain is minimized at each contact point, reducing thermal shock and mechanical stress on grain particles.
2Loss of energy
If heat reclamation is improved by recycling exhaust air, then energy efficiency is improved, but system complexity increases
Solution Approach 1:
The patent merges the cooling function and heat reclamation function into a single integrated counter-flow system. The same cooling air path serves dual purposes: cooling the grain while simultaneously being heated by exhaust air, eliminating the need for separate heat exchanger equipment and reducing overall system complexity despite improved energy recovery.
Solution Approach 2:
The system uses its own exhaust air to preheat the cooling air, creating a self-sustaining heat recovery loop. The exhaust air naturally flows through the system and transfers heat to the incoming cooling air without requiring external energy input or complex control systems, achieving energy efficiency through passive self-service.
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 design reduces grain breakage and fine material generation, improves heat reclamation efficiency, and decreases energy requirements by maintaining a more gradual cooling process and utilizing recycled warm air for drying, enhancing grain quality and processing efficiency.
Implementation Method 1
The blower draws air from the cooling plenum into the heater... Thus a negative pressure exists in the cooling plenum and a positive pressure exists in the heating plenum
Implementation Method 2
where its temperature is raised
Implementation Method 3
The cooling section includes an inner wall surrounded by an outer wall, which in combination define a cooling column through which cooling air flows in a counter-flow direction opposite to the direction of grain flow
Implementation Method 4
The inner and outer walls of the heating and cooling plenum, in combination, define an annular grain drying path... The inner and outer walls of the heating plenum are perforated (or otherwise air-permeable), as noted, so that heated air can pass through the drying path to dry the grain
Data Source
AI summary
A grain drying tower comprises a heater and blower separating a heating plenum and a cooling plenum. The dryer is provided with a heat reclamation/heat recycling system and/or counter-flow cooling to reduce the energy requirements of the tower dryer. The heat reclamation system comprises a chamber external to the outer wall of the tower and which is and located at a point along the drying path. The bottom of the chamber is open to the atmosphere. Hot exhaust air enters the heat reclamation chamber at the top of the chamber and is drawn back into the tower by the blower as the exhaust air exits the open bottom of the chamber. In the counter-flow, the walls defining the grain path of the in the cooling section are not air permeable, and air is drawn into the cooling section through outer wall ducts which are closed at the inner wall. The entering air travels up through heated grain to be warmed, and then enters the plenum through inner wall ducts, which are closed at the outer wall of the tower.