Fiber Bed Assembly for Mist Eliminator Re-entrainment Control
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Solution Overview
Problem
Re-entrainment of collected liquid from fiber bed separators in gas streams leads to fouling of downstream equipment, degradation of product purity, corrosion, and difficulty in meeting emission requirements, primarily due to gas phase drag causing bubbling and fragmentation of liquid droplets at high velocities.
Innovation Solution
A fiber bed assembly with a tubular shape and channel strips arranged to create overlapping regions, supported by a fiber bed support with inner and outer screens, includes a pre-filter media and drainage media to inhibit re-entrainment by managing liquid flow and gas velocity, using drainage inserts and re-entrainment inserts to direct liquid away from gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas stream velocity is increased to improve productivity, then emission removal efficiency improves, but liquid re-entrainment increases due to gas phase drag causing bubbling and fragmentation
Solution Approach 1:
The fiber bed is divided into multiple sections stacked vertically, with each section having its own drainage means. This segmentation allows liquid to be drained locally at each section rather than accumulating and draining from a single point, reducing gas phase drag effects and preventing re-entrainment even at high velocities
Solution Approach 2:
Drainage media is introduced as an intermediary layer between the collecting fiber media and the gas stream. This drainage media captures and channels liquid away from the gas flow path, preventing direct interaction between high-velocity gas and liquid that would cause bubbling and re-entrainment
2Object-generated harmful factors
If liquid is removed from the fiber bed to prevent re-entrainment, then re-entrainment is reduced, but downstream equipment fouling increases due to liquid moving to the discharge face
Solution Approach 1:
Drainage media acts as an intermediary that intercepts liquid within the fiber bed structure and directs it through dedicated drainage paths. This prevents liquid from reaching the downstream discharge face where it would cause fouling, while also preventing re-entrainment by keeping liquid away from the gas flow
Solution Approach 2:
Liquid is extracted from the fiber bed continuously at multiple points through the drainage means, removing it from the system before it can migrate to the discharge face or become re-entrained. This extraction occurs at the source rather than allowing liquid to accumulate and move downstream
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 effectively reduces re-entrainment of liquid and soluble solids, maintaining the fiber bed in a drier state, improving submicron particle collection efficiency and allowing operation at higher gas stream velocities with minimal pressure drop, thus reducing emissions and operational costs.
Implementation Method 1
The collecting fiber media is effective for the separation of liquid particulates (with or without solids dissolved or suspended therein) from gas streams
Implementation Method 2
aerosols, particularly of less than 3 microns, must be separated from a gas or vapor
Implementation Method 3
As the liquid drains down through the fiber bed and/or the downstream surface thereof
Implementation Method 4
This problem is particularly severe at the bottom of a vertically disposed fiber bed since all of the liquid collected by the fiber bed necessarily drains to the bottom and from a practical standpoint because of gas phase drag on the liquid, out the downstream surface at the bottom of the fiber bed
Data Source
AI summary
A fiber bed assembly for a mist eliminator that operates at high efficiency and inhibits re-entrained liquid from leaving the mist eliminator. The fiber bed assembly has a construction that facilitates rapid drainage of liquid collected by the fiber bed. A pre-filter media can be employed upstream of the primary collection media to remove larger liquid drops. The pre-filter media can be used in unique combination with other features to reduce liquid re-entrainment, and/or allow increased flow capacity.