Progressive Cavity Pump Catalyst Slurry Flow
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Solution Overview
Problem
Catalyst feed systems for polyolefin reactors face issues with non-uniform catalyst distribution, leading to overheating, fouling, and production losses due to the use of dosing and slurry feeders, which result in inconsistent polymerization rates and reactor instability.
Innovation Solution
A system utilizing a pressurized reservoir with a progressive cavity pump to transform highly viscous catalyst slurry into a syrup-like liquid, ensuring a controlled, continuous flow of particulate catalyst to the reactor, reducing viscosity and maintaining uniformity through moderate pressure drops and agitation, thereby preventing settling and fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dosing feeder is used to deliver catalyst slurry, then the catalyst can be fed into the reactor, but the catalyst distribution becomes non-uniform causing localized accumulation and overheating
Solution Approach 1:
The progressive cavity pump converts the traditional slug-based intermittent dosing into a continuous flow delivery system. The intermeshing rotor and stator create continuous cavities that move catalyst slurry steadily into the reactor, eliminating the start-stop dosing action and ensuring uniform continuous distribution throughout the reactor volume.
Solution Approach 2:
The invention replaces the mechanical dosing chamber and valve system with a progressive cavity pump system. Instead of using mechanical dosing mechanisms that create slugs, the pump uses the progressive cavity principle with a rotor-stator configuration to create a smooth continuous flow, substituting a different mechanical approach that inherently provides better distribution uniformity.
2Ease of operation
If catalyst slurry is delivered in slugs, then the dosing feeder can operate, but pumping instability occurs leading to loss of pumping and reactor plugging
Solution Approach 1:
The progressive cavity pump eliminates the slug-based intermittent flow by creating a continuous progressive motion. The rotating rotor continuously generates moving cavities that propel slurry forward without interruption, maintaining steady pumping action and preventing the pumping instability and plugging issues associated with slug delivery.
Solution Approach 2:
The invention changes the flow regime parameter from discontinuous slug flow to continuous progressive flow. By altering the fundamental delivery mode from intermittent to continuous, the system achieves stable pumping operation and eliminates the reliability issues associated with slug-based dosing.
3Ease of manufacture
If diluent is used to flush catalyst slurry, then the dosing chamber can be cleared, but fouling occurs due to polymerization in the dosing feeder mechanism
Solution Approach 1:
The progressive cavity pump's continuous flow action prevents catalyst slurry from stagnating in the delivery system. The constant movement of slurry through the pump and into the reactor eliminates the need for periodic flushing operations, thereby preventing fouling from occurring in the first place rather than requiring cleanup.
Solution Approach 2:
The invention extracts the flushing operation from the system by eliminating the need for it. The continuous flow design ensures complete evacuation of slurry from the pump and delivery lines, removing the condition that would require diluent flushing and thereby preventing fouling before it can occur.
4Ease of manufacture
If the catalyst slurry is highly viscous, then the catalyst can be handled in dry form, but the flow from the mud-pot becomes irregular causing variations in polymerization rate
Solution Approach 1:
The progressive cavity pump replaces gravity-based flow from the mud-pot with a positive displacement pumping system. The rotor-stator mechanism actively draws slurry from the mud-pot and delivers it at a controlled rate, substituting passive gravity flow with active mechanical pumping that ensures consistent flow regardless of slurry viscosity.
Solution Approach 2:
The invention changes the flow control parameter from gravity-dependent irregular flow to pump-controlled steady flow. By using the progressive cavity pump's positive displacement mechanism, the system maintains consistent flow rate and viscosity management, eliminating the irregularities that occur with gravity-based handling of viscous slurry.
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 system achieves consistent catalyst delivery, reducing variations in polymerization rates, minimizing reactor fouling, and extending operational uptime by maintaining a steady flow of catalyst without breaking particles or increasing frictional wear.
Implementation Method 1
a progressive cavity pump including a stator having an inlet connected to the reservoir outlet, an outlet connected indirectly to the polyethylene reactor, and a rotor disposed within the stator
Implementation Method 2
the viscosity of which is reduced by the application of a moderate pressure drop to a level which permits the progressive cavity pump to pump the catalyst slurry
Data Source
AI summary
Both a catalyst feed system and a method are provided for providing a flow, of a mud-like catalyst slurry into a polyolefin reactor. The system includes a pressurized reservoir of the catalyst having an outlet, and a progressive cavity pump including a stator and a rotor. The pump stator has an inlet connected to the reservoir outlet, and an outlet leading to the polyolefin reactor. In operation, the reservoir is first pressurized to a level a little higher than the pressure of the reactor. The outlet of the reservoir is opened and the progressive cavity pump is actuated. The pressure drop generated across the catalyst slurry contained in the reservoir by the pump causes the slurry diluent to flow between the interstices of the particles of catalyst. The thick, mud-like catalyst slurry is quickly transformed into a much less viscous, syrup-like slurry that flows from the reservoir outlet to the inlet of the pump stator. The progressive cavity pump then continuously conveys the catalyst through the stator outlet and into the reactor.