Recycle Gas Filter Top-Down Flow for Olefin Polymerization
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Solution Overview
Problem
Existing gas-phase fluidized-bed polymerization processes face challenges in maintaining high plant availability due to the formation of unstable filter cakes in recycle gas filters, which can lead to blockages and require frequent filter changes or shutdowns, especially when dealing with high dust loads from polymer particles.
Innovation Solution
The design of a recycle gas filter with an inlet chamber featuring a dividing wall that directs 60-90% of the gas flow onto the filter medium from the top downward, promoting a high gas throughput at low velocity and facilitating easy cleaning of the filter cake, while preventing redeposition of fine particles and reducing the risk of filter material erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas flows through the filter medium from below upward, then the filter cake builds up, but the filter cake becomes unstable and prone to blockages
Solution Approach 1:
The patent inverts the conventional flow direction by directing gas to flow through the filter medium from top to bottom instead of from below upward. This reversal prevents the formation of unstable filter cakes that blockage the filter, thereby improving filter operation stability while maintaining reliable particle separation.
2Productivity
If the filter is designed for high gas throughput, then productivity increases, but the filter cake builds up faster and requires more frequent cleaning
Solution Approach 1:
By inverting the flow direction to top-to-bottom, the patent enables high gas throughput while preventing rapid filter cake accumulation. The inverted flow pattern reduces the rate at which particles build up on the filter medium, thereby extending filter operating time even at high productivity levels.
3Productivity
If the filter medium is exposed to high velocity gas flow, then gas throughput is maintained, but the filter material erodes faster
Solution Approach 1:
The patent reverses the flow direction so that gas flows from top to bottom through the filter medium. This inversion reduces the erosive impact on the filter material by directing the high-velocity flow in a direction that minimizes mechanical degradation, thereby extending filter medium service life while maintaining adequate gas throughput.
4Reliability
If the filter cake is allowed to build up, then particle retention efficiency increases, but the filter becomes blocked and requires shutdown for cleaning
Solution Approach 1:
The patent inverts the conventional filtration approach by reversing the gas flow direction. This inversion allows the filter to maintain high particle retention efficiency while preventing the filter cake from reaching blockage levels, thereby eliminating plant shutdowns for filter cleaning and improving overall plant availability.
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
This configuration significantly extends the operating time of the filter, achieving filter efficiencies above 99% and preventing the formation of unstable filter cakes, thus ensuring high plant availability and reducing the need for frequent filter replacements.
Implementation Method 1
an essentially vertical sheet-like filter medium for retaining the fine particles which separates the inlet chamber from the outlet chamber
Implementation Method 2
flow along the filter medium from the top downward... The formation of a filter cake which can readily be cleaned off is aided by the cleaning of the filter being achieved both by means of gravity and by means of the gas flowing onto the filter from the top downward
Data Source
AI summary
Apparatus for the polymerization of olefins, in particular ethylene, comprising a gas-phase fluidized-bed reactor (1), a product offtake line (15) for taking polymer particles either continuously or discontinuously from the reactor (1), which line (15) is connected to a depressurization vessel (2) for separating polymer particles and gas, a recycle gas filter (3) for freeing the gas of entrained fine particles connected to the depressurization vessel (2), a compressor which compresses the gas which has been freed of fine particles and recirculates it into the reactor (1), with the recycle gas filter (3) having an inlet chamber (4) provided with a gas inlet (6), an outlet chamber (5) provided with a gas outlet (7), an essentially vertical sheet-like filter medium (9) for retaining the fine particles which separates the inlet chamber (4) from the outlet chamber (5) and a particle outlet (8). The inlet chamber (4) has a dividing wall (10) which is arranged essentially parallel to the filter medium (9) and separates the inlet chamber (4) into an inflow region (4a), which is connected to the gas inlet (6), and a filter region (4b) in which the filter medium is located and has an upper opening and a lower opening which are dimensioned so that from 60 to 90% of the volume flow flows through the upper opening so that flow along the filter medium (9) from the top downward results.