Valveless Piston Pump Catalyst Slurry Feeding
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Solution Overview
Problem
Existing methods for feeding solid polymerization catalysts into reactors are not well-suited for catalysts with low productivity, as they require high feed rates, leading to catalyst attrition and oil residue in the polymer product, especially when using metallocene catalysts.
Innovation Solution
A process involving a catalyst slurry with a diluent of low viscosity (0.01 to 20 mPa·s) is maintained in a catalyst feed vessel and transferred using a valveless piston pump along a vertical path to the reactor, allowing for accurate and reliable feeding of catalysts with varying productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the catalyst feed rate is increased to compensate for low productivity catalysts, then the catalyst can be fed in sufficient quantities, but catalyst attrition and disintegration occurs
Solution Approach 1:
A diluent is introduced as an intermediary substance to create a catalyst slurry. This slurry form allows the catalyst to be transported and fed at higher rates without direct particle-to-particle contact and mechanical stress, thereby preventing attrition while maintaining sufficient feed rates for low-productivity catalysts
Solution Approach 2:
The catalyst is transformed from a dry solid state to a slurry state by changing its physical form and introducing a diluent. This parameter change enables the catalyst to be handled and fed differently, allowing higher feed rates without damage to particle integrity
2Stability of the object's composition
If intensive mixing is used to maintain homogeneous catalyst slurry, then the slurry remains uniform, but energy input leads to catalyst attrition
Solution Approach 1:
Instead of using intensive continuous mixing, the system uses minimal or intermittent mixing action sufficient to maintain slurry homogeneity. The diluent provides natural suspension, allowing the catalyst to remain uniformly distributed without excessive mechanical energy input that would cause attrition
3Ease of operation
If oil is used as diluent in catalyst feed, then the catalyst can be suspended and fed, but oil remains in the finished polymer product as extractable matter
Solution Approach 1:
The harmful oil residue is extracted or removed from the system by selecting a diluent that does not remain in the final polymer product. The diluent is chosen to be completely removable or inert, taking the harmful extraction issue out of the process
Solution Approach 2:
The chemical composition and properties of the diluent are changed from traditional oils to alternative substances (such as supercritical fluids or inert gases) that do not leave residues in the polymer, fundamentally changing the parameter of diluent composition to eliminate harmful effects
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 method prevents catalyst attrition, reduces oil residue in the polymer product, and allows for a wide range of catalyst activities, providing a stable and accurate feeding system with low investment costs.
Implementation Method 1
the catalyst slurry is transferred by using a valveless piston pump from the catalyst feed vessel into the polymerisation reactor
Data Source
AI summary
The present invention is directed to a process for feeding a polymerisation catalyst into a polymerisation reactor (7), comprising the steps of: (i) maintaining a catalyst slurry comprising a diluent and a solid catalyst component in a catalyst feed vessel (4); (ii) continuously withdrawing a stream of the catalyst slurry from the catalyst feed vessel (4); and (iii) introducing the withdrawn portion of the catalyst slurry into the polymerisation reactor (7), wherein the catalyst slurry is transferred by using a valveless piston pump (5) from the catalyst feed vessel (4) into the polymerisation reactor (7); the diluent has a dynamic viscosity of from 0.01 to 20 mPas at the conditions within the catalyst feed vessel (4), and wherein the catalyst slurry is transferred along a substantially vertical path downwards from the catalyst feed vessel (4) to the reactor (7).