Hot Gas Cyclone Drying for Cleaner Wood Fiber Heat Recovery
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Solution Overview
Problem
Existing methods for drying wood fibers and wood chips in drum dryers face issues with heat exchanger degradation due to deposition of solid particles from burner exhaust gases, leading to reduced efficiency and increased maintenance costs, as well as inefficient energy utilization of exhaust gases.
Innovation Solution
Incorporation of a hot gas cyclone operated below the ash sintering point with a continuous ash/soot discharge system, combined with a multi-fuel and solid fired hot gas generator, to effectively remove solid particles and recycle thermal energy from exhaust gases, using preheated combustion air to enhance efficiency and reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hot gas cyclone is used for continuous drying of bulk goods, then drying capacity and efficiency are improved, but the complexity of the drying system increases due to additional components
Solution Approach 1:
The patent combines the drying function and separation function into a single integrated hot gas cyclone device. The cyclone simultaneously dries the bulk goods with hot gas while separating the dried material from the gas stream, eliminating the need for separate drying and separation equipment. This merging approach increases drying capacity while managing system complexity through functional integration.
Solution Approach 2:
The hot gas cyclone performs multiple functions within a single device: it acts as a drying chamber, a separation device, and a gas-solid contactor. The cyclone's design allows it to handle both the thermal processing and mechanical separation tasks that would traditionally require separate equipment, making the system more versatile and efficient.
2Duration of action of stationary object
If drying is performed in batches using conventional equipment, then system complexity is kept low, but production time and energy consumption increase
Solution Approach 1:
The hot gas cyclone enables continuous drying operation where bulk goods are constantly fed into the cyclone and dried material is continuously discharged. This eliminates the start-stop nature of batch processing, maintaining continuous thermal action and gas flow. The continuous operation reduces total production time and improves energy efficiency by avoiding repeated heating cycles and idle periods between batches.
3Power
If hot gas cyclone technology is implemented, then drying efficiency increases, but the difficulty of detecting and measuring process parameters increases
Solution Approach 1:
The patent incorporates measurement devices and sensors as intermediaries to detect and monitor process parameters within the cyclone. These intermediaries include temperature sensors, pressure transducers, and flow meters that translate internal cyclone conditions into measurable signals. This approach maintains high drying efficiency while enabling proper monitoring and control of the drying process.
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 solution prevents heat exchanger degradation, maintains high efficiency, reduces maintenance, and optimizes energy use by recycling thermal energy, while minimizing emissions and improving the quality and safety of the drying process.
Implementation Method 1
a hot gas cyclone (2) downstream of the converter (1), wherein the hot gas cyclone (2) is configured to separate the bulk goods (3) from the gas flow (4)
Implementation Method 2
the hot gas cyclone (2) is configured to separate the bulk goods (3) from the gas flow (4) by means of a centrifugal action
Implementation Method 3
a converter (1) configured to heat the bulk goods (3) with a hot gas flow (4)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to an apparatus and a method for continuously drying bulk goods, in particular wood fibers and/or wood chips, in a dryer, wherein the drying vapors are led to a dryer circuit, in which the drying vapors are indirectly heated via a heat-exchanger (4) and are conducted to the dryer (1) again.