Air Lance Nozzle for Catalyst Pellet Unloading
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Solution Overview
Problem
Existing methods for unloading catalyst pellets from reactor tubes face challenges due to bridging issues, where smaller nozzles reduce bridging but result in lower air flow and force, while larger nozzles increase bridging, and require higher compressed air pressures, which is inefficient and costly.
Innovation Solution
A nozzle design that achieves supersonic flow and higher air volume with a smaller diameter, reducing bridging opportunities, combined with a thin rod for operator feedback and pellet dislodgment assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a smaller nozzle is used to reduce bridging, then bridging is reduced, but the volume of air delivered and force exerted on catalyst pellets decrease
Solution Approach 1:
The nozzle design changes the flow parameters by creating a converging-diverging geometry that transforms subsonic flow to supersonic flow. This parameter change allows the smaller nozzle to deliver the same or greater force despite the reduced diameter, resolving the contradiction between reducing bridging and maintaining force.
Solution Approach 2:
The nozzle utilizes dynamic flow transitions where the air flow accelerates from subsonic to supersonic speeds through the converging-diverging passage. This dynamic behavior allows the system to overcome the static limitation of nozzle size, maintaining high force output while using a smaller nozzle diameter to reduce bridging.
2Force
If a larger nozzle is used to deliver more compressed air volume, then force on catalyst pellets increases, but bridging increases
Solution Approach 1:
By changing the flow regime from subsonic to supersonic through the converging-diverging nozzle geometry, the system achieves higher air velocity and volume delivery without increasing nozzle diameter. This resolves the contradiction by decoupling force delivery from nozzle size.
Solution Approach 2:
The invention utilizes pneumatic principles by designing a nozzle that leverages compressed air's compressibility and expandability. The converging-diverging geometry transforms pressure energy to kinetic energy efficiently, delivering high force with a compact nozzle that minimizes bridging.
3Force
If higher compressed air pressure is used to increase air flow through a small nozzle, then force increases, but access to higher pressure sources is required and pressure drop increases
Solution Approach 1:
The nozzle design changes the pressure-velocity relationship by creating supersonic flow conditions. This allows the system to achieve high force delivery at moderate inlet pressures by efficiently converting pressure to velocity in the converging-diverging passage, reducing the need for high-pressure sources.
Solution Approach 2:
The nozzle utilizes a flow regime transition analogous to phase change, where subsonic flow transitions to supersonic flow at the throat. This transition allows the system to dramatically increase air velocity and force delivery without proportionally increasing inlet pressure, simplifying the compressed air source requirements.
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 a higher output force and volume of air, reducing bridging and improving catalyst unloading efficiency with a smaller nozzle, minimizing reactor shutdown time and production losses.
Implementation Method 1
pressurized air is used to dislodge and fluidize the catalyst pellets, which are then evacuated from the top of the tube using a vacuum arrangement
Implementation Method 2
a vacuum arrangement... to pull out the air being injected by the air lance, together with the fluidized pellets
Implementation Method 3
a smaller nozzle will deliver a smaller volume of air, which results in a lower force being exerted on the catalyst pellets by the stream of pressurized air exiting the nozzle
Data Source
AI summary
An air lance for removing pellets from tubes may include a nozzle with an inner surface having converging and diverging portions adjacent the downstream end of the nozzle to improve air flow. The air lance may include a projection fixed relative to the nozzle and extending beyond the downstream end of the nozzle to serve as a feeler, a poker, and a spacer.