Parallel Flow Rotary Dryer with Knock-Out Box for Fracking Sand
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Solution Overview
Problem
Fine particulate materials, such as 100-140 mesh sand used in hydraulic fracturing, are difficult to dry efficiently due to their fine nature, which causes them to envelop the flame in direct fired burner dryers, leading to inefficiency and loss of dried particles in dust collection systems.
Innovation Solution
A device and method involving a separate combustion chamber to house the burner flame, preventing direct contact between the fine sand and the flame, and utilizing a parallel flow rotary dryer with a knock-out box and a baffle to separate and slow down effluent gases, ensuring effective particle separation and collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a direct fired burner dryer is used to dry fine particulate material, then the drying process can be implemented, but the fine particles envelop the flame rendering the process inefficient and causing particle loss in dust collection systems
Solution Approach 1:
The dryer is segmented into distinct zones: a combustion chamber for flame generation and a drying chamber for particle processing. This spatial segmentation prevents fine particles from contacting the flame directly, eliminating the envelopment problem while maintaining drying efficiency.
Solution Approach 2:
Hot effluent gases from the combustion chamber serve as an intermediary heating medium. Instead of direct flame contact, these hot gases transfer thermal energy to the fine particles in the drying chamber, achieving efficient drying without particle loss.
2Manufacturing precision
If the knock-out box is made large enough to slow effluent velocities, then particle separation should improve, but effluent gases take the path of least resistance at higher velocities carrying fine particles to the dust collection system
Solution Approach 1:
The baffle introduces a new spatial dimension to the flow path. By placing longitudinal elements that extend across the effluent flow, the system forces gases to navigate around obstacles, converting a simple linear flow into a multi-dimensional path that increases residence time and separation efficiency.
Solution Approach 2:
The baffle elements are positioned to create a pressure drop that forces effluent gases to skip around the longitudinal elements rather than flowing directly. This skipping motion increases the path length and residence time in the knock-out box, improving particle separation despite the large box size.
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 enables efficient drying of fine particulate materials by preventing flame envelopment and optimizing gas flow, resulting in high particulate recovery rates, such as 99.5%, and reduced operational challenges in dust collection systems.
Implementation Method 1
a burner (41) that generates a flame (40)
Implementation Method 2
The sand and the hot effluent gases from the burner travel in a parallel flow arrangement to the output end of the dryer, with the hot gases heating the sand and driving the moisture out of the sand
Implementation Method 3
which slows down the velocity of the effluent gases to allow the entrained dry particles to fall out of the flow stream
Data Source
AI summary
A device and method for drying fine particulate. A parallel flow rotary drum dryer is used to dry the particulate material. There is a combustion chamber for the burner, located upstream of the dryer inlet, and the burner flame is limited to the combustion chamber so the fine particulate material does not come into direct contact with the burner flame. The output from the dryer passes through a knock-out box including a baffle system with a plurality of narrow gaps to create a pressure drop to slow down the gas flow and enable the entrained fine mesh dry particulate to drop out through a bottom outlet before the effluent gas is sent to the dust collection/air filtration system.