Wurster Accelerator Powder Applicator
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Solution Overview
Problem
In the pharmaceutical industry, Wurster coating processes using polymer suspensions and solutions often face issues with glidant aggregation and sedimentation, leading to spray gun and line plugging, reduced polymer application rates, and inefficient coating due to the need to suspend glidants in the polymer solution, which reduces their effectiveness and increases production costs.
Innovation Solution
A modified Wurster accelerator system that applies dry, finely divided powders using a vacuum-generating eductor and radial holes in the diverter sleeve, eliminating the need for glidants in the suspension or solution, thereby preventing agglomeration and allowing higher polymer content and faster application rates without interfering with the spray pattern or product movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If glidant is suspended in polymer solution for spray application, then polymer coating can be applied, but glidant aggregates and sediments causing spray gun and line plugging
Solution Approach 1:
The system separates the glidant application from the polymer spray by using a separate powder feed mechanism. The glidant is applied as dry powder through a powder feed line and diverter sleeve, while the polymer solution is sprayed through a separate spray gun, preventing mixing and thus preventing plugging while maintaining both functions
Solution Approach 2:
The glidant is extracted from the polymer solution and applied separately as dry powder. This removes the harmful aggregation and sedimentation issues associated with suspending glidant in the polymer solution, while still achieving the desired coating effect through combined application
2Productivity
If glidant is included in polymer suspension, then polymer can be applied, but polymer application rate is reduced due to glidant content
Solution Approach 1:
The system applies polymer and glidant through separate mechanisms - polymer solution is sprayed while glidant powder is fed separately through a powder feed line. This allows maximum polymer concentration in the spray without dilution from glidant, achieving higher polymer application rates
Solution Approach 2:
The glidant is changed from a suspended state in the polymer solution to a dry powder state applied separately. This parameter change allows the polymer solution to have higher polymer concentration without the constraints of glidant suspension requirements
3Reliability
If glidant is coated with polymer during spray application, then polymer coating is formed, but glidant effectiveness in reducing aggregation is reduced
Solution Approach 1:
The glidant is extracted from the polymer coating process and applied as dry powder directly to the substrate. This maintains the glidant's effectiveness in reducing aggregation without being diluted or coated by polymer, while the polymer is applied separately through the spray gun
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 approach prevents agglomeration, reduces process time, and increases the efficiency of glidant use, allowing for higher polymer application rates and minimizing line and gun plugging, thereby improving the overall coating process and reducing production delays.
Implementation Method 1
replacing the original accelerator diverter sleeve compressed air supply with a vacuum generating eductor thereby causing powder to be entrained into the diverter air flow
Implementation Method 2
causing powder to be entrained into the diverter air flow and distributed via the plurality of (radial) holes of the diverter sleeve
Data Source
AI summary
A Wurster processor and a powder feed system are coupled via an eductor so as to supply dry powder through the air diverter sleeve of the Wurster for discharging onto the circulating particles during operation of the Wurster. Agglomeration and aggregation of the particles is eliminated or minimized by isolating or separating the liquid spray by the spray gun from the dry powder.