Manufacturers are increasingly turning to on-line particle size analysis because of its proven ability in transforming process control and providing significant economic benefits in terms of lower energy consumption, higher throughput, lower energy consumption, reduced waste and improved product quality.
As a result, on-line particle size analysis is widely used across the processing industries. This article reviews the range of options around project implementation, how to use them, and their effect on the success of the overall project. In addition, advantages and disadvantages of different implementation strategies are also assessed through a case study.
On-line Laser Diffraction Particle Size Analysis
Generally, a number of steps are involved in the installation of on-line particle size analysis and they include process interface design, hardware selection, integration and automation into an existing control platform, substantiation, and commissioning and control optimization.
Although a number of on-line techniques are still new, on-line laser diffraction particle size analysis is comparatively advanced and is proven across a range of industries. Early adopters of this technique have led the way in dealing with implementation problems. As a result, there is now a secure knowledge base that covers almost any type of application. New users now have options in terms of implementation strategy that ranges from simply buying a sensor to handing the entire project over to the instrument supplier.
Each project is unique and the risk-reward balance changes from case-to-case. However, the core elements of an on-line sizing project are shared. When each of these elements is looked in turn, it helps in assessing which areas can be possibly handled in-house, and where external support may prove particularly useful.
In any particle sizing project, the first step is to identify hardware that meets the required specification. In order to choose the optimum solution, it is also vital to consider how often the process has to be measured. Real-time laser diffraction particle size analyzers can rapidly measure complete particle size distributions but in certain cases this is more than is strictly required.
For instance, if the process has slow dynamics, a single sensor will be able to cover various points in the process, thus increasing the potential benefit. As a result, this can have a positive effect on the economic case.
Process Interface Design
An important issue for particle size measurement is reliable, representative sampling because failures in this area are usually the main source of error in reported data. One simplest option is in-line laser diffraction measurement and is utilized wherever applicable.
However, for highly concentrated streams or high tonnage flows, it is important to install the analyzer on-line, on a discrete sampling loop. A representative stream is constantly extracted from the process, circulated via the loop, measured and then stored separately.
Significant attention is paid to this aspect of the project and hence many people seek expert support in the design of the interface, as an inferior design can compromise the whole project.
Malvern Panalytical is one of the few companies that offer a consultancy service to address this aspect of the project and identify an optimal solution via an on-site trial. Such consultancies, besides validating the most suitable interface design, offer guarantee that the technology will meet expectations.
A continuous particle size analyzer may have minimum automation and can operate through a computer, with just clean air and power. However, the trend towards multivariate control has led to major advances in supporting software and hardware.
One prominent development has been the OPC architecture, a standardization designed to integrate a range of instruments from different suppliers in just one control system.
Therefore, the development of multivariate control systems is becoming easier and there are firms that deal in this provision. However, there are many different systems that are being used across the processing industries. It should be noted that even if the original scope of the project is simple QC, it is evident that real-time analysis usually delivers the highest return when used to automate control.
Laser diffraction continuous particle size analyzers provide complete particle size distributions. Options here depend on which particular elements of the particle size distribution define product performance appropriately.
These may be identified once real-time sizing is in place. In the last stages of the project, the support of an instrumentation engineer who is familiar with the system and its operation can prove extremely useful.
Project Implementation Strategy
Several choices can be made to customize the project implementation strategy to meet user needs. The following example shows how these choices can be put into practice to address different requirements.
One particular company mills batches of powder coatings and uses a plant that is manually operated. Here, particle size is controlled by modifying the conditions of the mill on the basis of lab results determined through a laser diffraction analyzer.
Continuous particle size analysis is viewed as a possible option to lower manual input, higher throughput and better product quality; however there is minimal engineering support and CAPEX is extremely limited. Despite the fact that this company has little in-house expertise for project implementation, its needs are comparatively simple.
The best option here would be to use a sensor to cut down CAPEX to an accessible level. Using in-house knowledge and freely available literature, the company can design and produce a simple process interface. Although some experimentation may be needed to optimize data use, existing company experience with the analytical technique will help.
A successful project is one that delivers the required return in the expected timeframe. In order to achieve this objective, it is important to be realistic about how the project will turn out and what it will cost in terms of expertise, money and time to realize these benefits.
In addition to the choice of on-line laser diffraction particle sizing, one should be practical about in-house strengths and limitations to access the technology in the best possible way and gain maximum benefit.
This information has been sourced, reviewed and adapted from materials provided by Malvern Panalytical.
For more information on this source, please visit Malvern Panalytical.