Hardened Catalyst Metering Valve for Wear Resistance
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Solution Overview
Problem
The adhesion and degradation of particulate catalysts, such as silica-supported catalysts, lead to mechanical wear and unstable feeding in catalyst metering systems during polyethylene polymerization, resulting in unintended changes and suboptimal reaction conditions.
Innovation Solution
A catalyst metering device featuring a rotatable valve made of iron-based alloy steel hardened to a Rockwell hardness of at least 60, with specific compositions of carbon, chromium, manganese, molybdenum, silicon, and vanadium, which reduces leakage and jamming, enabling precise and controlled dosing of abrasive and viscous catalyst slurries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional materials are used for the catalyst metering valve, then the device is easier to manufacture and operate, but mechanical wear occurs leading to shorter lifetime and unstable feeding
Solution Approach 1:
The patent applies composite materials by using an iron-based alloy steel with specific composition (0.2-0.6% C, 1.0-2.0% Si, 0.5-1.5% Mn, 1.0-2.0% Cr, 0.1-0.5% Mo, 0.1-0.5% V) hardened to Rockwell C 58-63. This composite material structure provides both manufacturing feasibility and exceptional wear resistance, resolving the contradiction between ease of manufacture and extended device lifetime when handling abrasive catalyst slurries
2Reliability
If conventional materials are used for the catalyst metering valve, then the manufacturing cost is lower, but mechanical wear and degradation occur leading to unstable catalyst feeding
Solution Approach 1:
The patent changes the material parameters by specifying precise alloy composition ranges and hardness values (Rockwell C 58-63). This parameter optimization ensures the valve material has sufficient hardness to resist abrasive wear from silica-supported catalyst particles while maintaining dimensional stability, thereby ensuring reliable and stable catalyst feeding over extended operational periods
3Strength
If the valve material is hardened to high Rockwell hardness, then wear resistance improves, but the material becomes more difficult to manufacture and process
Solution Approach 1:
The patent optimizes the material parameters by defining specific alloy composition ranges (0.2-0.6% C, 1.0-2.0% Si, etc.) and target hardness values (Rockwell C 58-63). This balanced parameter selection achieves high wear resistance while maintaining manufacturability, as the controlled alloy composition allows for manageable heat treatment and machining processes despite the high hardness requirement
Data Source
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AI summary
The invention relates to a catalyst metering device with a valve formed of an iron-based alloy steel hardened to a Rockwell hardness C of at least 60. The device can be used for metering of a catalyst for an ethylene polymerization reaction. The invention further relates to ethylene polymerization wherein the catalyst is metered in a catalyst metering device with a iron-based alloy steel hardened valve, as well as to a ethylene polymerization reactor comprising such a catalyst metering device.