On-line particle size analysis is being implemented across many processing industries, thanks to its proven ability to change process control and deliver significant economic benefits in terms of higher throughput, lower energy consumption, reduced waste, and improved product quality. As manufacturers adopt on-line particle size analysis, the issue of how best to implement a successful project becomes highly relevant.
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This article explores different options for the design and implementation of on-line particle sizing, emphasizing the practical benefits of selecting the one which is appropriate for the specific project.
Setting Realistic Expectations
Despite the fact that several on-line techniques are still relatively new, on-line laser diffraction particle size analysis is well-established across a range of industries. Early adopters of on-line particle size analysis have led the way in overcoming implementation problems. As a result, there is now a safe knowledge base encompassing virtually every type of application. Therefore, new users have options in terms of implementation strategy that ranges from procuring a sensor to handing the entire project over to the instrument supplier.
The first and most important step in any particle sizing project is to identify hardware that satisfies the required specification. To choose the best solution, it is vital to consider how often the process needs to be measured. For instance, real-time laser diffraction particle size analyzers can measure complete particle size distributions within a second, but in some situations this is not strictly required.
If instant upset detection is not important or if the process has slow dynamics, then a lower measurement frequency can be sufficient. In such instances, a single sensor might be able to cover various points in the process, thus improving the potential benefit.
Process Interface Design
Analytical instrumentation, which is developed for constant use in the plant environment, must integrate and interface with the process. A major issue in particle size measurement is reliable, representative sampling because failures in this area are usually the main source of error in reported data. The simplest option would be to use in-line laser diffraction measurement, as this can be utilized wherever practicable. However in some situations, in highly concentrated streams for instance, the analyzer has to be installed on-line, on a discrete sampling loop.
Malvern Panalytical offers a consultancy service to deal with this aspect of the project and identifies an optimal solution through an on-site trial. Such services, in addition to validating the most suitable interface design, provide confidence that the technology will deliver to expectations.
Automation and Integration
A continuous particle size analyzer, in the simplest case, may include a bare minimum of automation, functioning through a stand-alone computer, with clean air and power being the only additional requirements. However, the trend towards multivariate control has given way to major advances in supporting software and hardware.
One such prominent development has been the introduction of the OPC architecture, a standardization specifically designed to make it easier to combine a range of instruments in a single control system. The development of multivariate control systems is becoming easier, and options in the area of automation hardware and related software are numerous.
Validating the Solution
Validation needs are an important element in some industries, particularly in the pharmaceutical industry, and these requirements differ from industry to industry. Standard requirements may include:
- Site acceptance testing
- 21 CFR Part 11
- IQ/OQ testing and documentation
- Factory acceptance testing
In addition, an audit of the supplying company may be required.
Commissioning and Control Optimization
Fast and effective commissioning is very important, but equally important is to ensure optimal usage of the resulting data. If the goal is automated control, then the main aim is to close the control loop rapidly and efficiently. To this end, laser diffraction continuous particle size analyzers provide complete particle size distributions. In other words, control - whether automated or manual - can be based on any number of parameters, for instance, % below 5µm, between 3 and 30µm, or more than 200µm, or a combination of parameters. Here, options depend on which particular elements of the particle size distribution optimally define the performance of product.
A successful project provides the desired outcome within the proposed timeframe. Key to achieving this objective is being realistic about how the project will transform operation and what it will involve in terms of expertise, time and money to realize these benefits. A major aspect of these considerations is how best to execute the project.
The development of on-line laser diffraction particle sizing has introduced a range of options as to how best to work with a supplier, when using the technology. Being practical about in-house strengths and limitations is important in choosing the most appropriate approach and to using the technology in the best possible way.
This information has been sourced, reviewed and adapted from materials provided by Malvern Panalytical.
For more information on this source, please visit Malvern Panalytical.