Mixed-flow grain dryer with cross-flow vacuum heat recovery
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Solution Overview
Problem
Existing grain dryers, such as cross-flow and mixed-flow dryers, face issues like harsh treatment of grain, uneven drying, high energy consumption, fuel inefficiency, and maintenance challenges, leading to over-drying, damage, and variability in grain quality.
Innovation Solution
A mixed-flow grain dryer with a cross-flow vacuum cool heat recovery system that uses a centrally positioned plenum to facilitate gentle and efficient drying, incorporating a heating section with inlet and exhaust ducts and a cooling section with perforated walls for even air flow and heat recovery, reducing energy consumption and grain damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cross-flow grain dryers use heated air blown through grain columns, then grain drying efficiency is improved, but grain quality deteriorates due to harsh treatment causing cracking and burning
Solution Approach 1:
The patent inverts the conventional cross-flow drying approach by using vacuum cooling instead of heated air blowing. The system draws air through the grain columns from bottom to top using vacuum, creating a gentler drying environment that prevents grain damage while maintaining drying efficiency.
Solution Approach 2:
The patent changes the thermal parameters from high-temperature heated air to lower-temperature vacuum cooling. By controlling the vacuum level and air flow rate, the system achieves effective drying at temperatures that do not cause grain cracking or burning.
2Quantity of substance
If mixed-flow grain dryers heat grain in grain columns, then moisture removal is improved, but energy consumption increases
Solution Approach 1:
The patent recovers heat from the air that has passed through the grain columns during vacuum cooling. This recovered heat is then reused in the drying process, significantly reducing the energy required for moisture removal and improving overall fuel efficiency.
Solution Approach 2:
The system maintains continuous air flow through the grain columns during both drying and cooling phases. The vacuum system operates continuously to draw air through the grain, ensuring uninterrupted moisture removal while the recovered heat continuously supports the drying process.
3Reliability
If grain is overly dried to ensure low moisture content, then storage stability is improved, but grain value deteriorates due to damage and reduced test weight
Solution Approach 1:
The patent incorporates moisture sensing feedback to monitor grain moisture content in real-time during the drying process. When the grain reaches the optimal moisture level for storage stability, the system automatically adjusts or stops the drying process, preventing over-drying and associated grain damage.
Solution Approach 2:
The system dynamically adjusts the vacuum level and air flow rate based on the grain's drying progress. As moisture content decreases, the vacuum pressure and air flow are reduced to prevent excessive drying, maintaining grain quality while ensuring storage stability.
4Speed
If cross-flow grain dryers use high air-flow and high operating pressure, then drying speed is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent replaces the complex high-pressure mechanical blowing system with a simpler vacuum suction system. The vacuum pump creates negative pressure to draw air through the grain columns, achieving effective drying at lower absolute pressures and reducing the complexity of pressure control mechanisms.
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 achieves efficient, gentle grain drying with reduced fuel consumption, even moisture distribution, and improved grain quality, minimizing maintenance and the risk of over-drying while enabling precise control and heat recovery.
Implementation Method 1
Air is pulled through the perforated exterior wall, through the grain column and through the perforated interior wall and into the cool plenum under vacuum formed by a fan
Implementation Method 2
As the air is pulled through the grain column of the cooling section, the grain is cooled and the air is heated
Implementation Method 3
This heated air is heated further by a heater. This heated air is then blown into the heat plenum
Implementation Method 4
As the heated air blows through the columns of grain, the heated air warms the grain and carries away moisture from the grain
Implementation Method 5
heated and pressurized air in the heat plenum gently flows through the grain column
Implementation Method 6
under vacuum formed by a fan connected to the cool plenum of the cooling section
Data Source
AI summary
An improved grain dryer is presented having a mixed-flow heating section having a plurality of inlet ducts connected to the plenum that facilitate air flow into the grain column from the heated and pressurized heat plenum, and a plurality of exhaust ducts connected to openings in the exterior wall that facilitate air flow out of the grain column. A tempering section is positioned below the heating section and includes solid walls that reduce air flow through the grain column. A cooling section is positioned below the tempering section and includes perforated walls that facilitate air flow through the grain column and into the plenum. In use, heated air is forced outward through the mixed-flow heating section heating and drying the grain and air is pulled through the cross-flow cooling section cooling the grain. Air pulled through the cross-flow cooling section is recycled into the mixed-flow heating section thereby recycling heat.