Low Friction Solids Feeder for Catalyst Injection
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Solution Overview
Problem
Existing catalyst feeders face challenges in operating at low rotation speeds without stalling or overheating, particularly when handling high activity catalysts and varying production rates, leading to limited turndown ratios and difficulties in feeding small amounts of catalyst during reactor start-up.
Innovation Solution
The use of a solids feeder with components in moving contact coated with low friction materials, such as glass-filled polytetrafluoroethylene (PTFE), reduces friction and torque requirements, allowing operation at lower rotation speeds without stalling or overheating the drive motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the metering disc rotates at low speed to feed small amounts of catalyst, then the catalyst injection rate can be reduced, but the drive motor stalls or overheats due to high torque requirements
Solution Approach 1:
The metering disc cavities are pre-filled with catalyst particles before rotation begins. This preliminary action allows the disc to transport pre-positioned catalyst batches without requiring continuous high torque during rotation, enabling low-speed operation while maintaining reliable motor function.
Solution Approach 2:
The catalyst feed is divided into discrete batches corresponding to individual cavities in the metering disc. Each cavity independently holds and transports a portion of the catalyst, allowing the system to operate at low speeds with reduced torque requirements while maintaining precise control over catalyst injection rates.
2Productivity
If the metering disc rotates at high speed to increase catalyst injection rate, then productivity improves, but the turndown ratio is limited and small amount feeding becomes difficult
Solution Approach 1:
The system dynamically adjusts catalyst injection rates by varying rotational speed across a wide range. The segmented cavity design enables effective operation at both high speeds (for maximum productivity) and low speeds (for start-up conditions), achieving a broad turndown ratio that adapts to different production requirements.
Solution Approach 2:
The system changes operational parameters by adjusting rotational speed to match production demands. The discrete cavity architecture allows maintaining precise metering control across varying speeds, enabling the system to transition smoothly between high-rate production mode and low-rate start-up mode.
3Reliability
If conventional sealing materials are used between the metering disc and cover plate, then sealing is achieved, but friction and torque requirements increase
Solution Approach 1:
Conventional mechanical sealing materials (such as rubber or polymer seals) are replaced with magnetic field-based sealing. Magnets embedded in the metering disc interact with a ferromagnetic cover plate to create sealing force, eliminating the need for high-friction mechanical contact while maintaining effective sealing.
Solution Approach 2:
A ferromagnetic cover plate acts as an intermediary between the magnetized metering disc and the external environment. This intermediary creates magnetic attraction forces that provide sealing pressure without requiring direct mechanical contact, thereby reducing friction and torque 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 the solids feeder to operate at lower rotation speeds with reduced torque requirements, preventing motor stalling and overheating, and providing a broader range of catalyst injection rates, thus addressing the limitations of existing feeders.
Implementation Method 1
components in moving contact with one another are provided with a surface comprising a low friction material, such as, for example, glass-filled polytetrafluoroethylene (PTFE), to reduce the friction between the surfaces
Data Source
AI summary
An apparatus for feeding a dry particulate solid into a pressurized vessel including: a solids reservoir; a rotating metering disc below the solids reservoir; a non-rotating component adjacent to the metering disc; a surface of contact between the metering disc and the non-rotating component, wherein the surface of contact comprises a low friction material; a drive shaft, a drive motor; a pickup section; and an injection tube is provided.