Online sensor technology

by Urs Dübendorfer
Share This:

Topics such as food safety, traceability, or best practice are of great importance to today’s millers. Finding the time to fulfill these requirements is a common concern. By assisting the operators with online sensing and intelligent automatisms, additional resources can be gained.

The newly developed NIR online analyzer and the online particle size measurer are eligible solutions to fulfill this task.

For many years, online NIR analyzers have been used for continuous monitoring of the constituents of raw and finished products in the grain processing industry. But very often limits are set due to remarkable investments. Consequently, the monitoring points must be chosen very carefully.

With the goal of expanding the possible applications, Bühler AG, Uzwil, Switzerland, has developed a new generation of NIR online analyzers. By introducing the so-called multiplexer technology, millers are able to measure many points with a limited investment. One spectrometer evaluates up to six different measuring points. Of course, the measuring device works with the most recent diode array technology.

The benefits of the NIR multi online analyzer are obvious: a central spectrometer enables real-time analysis of different products like cereals, flour and even byproducts. Up to six independent measuring points provide the base for an intelligent control of the running production.

NIR improves the consistency of the product quality and thus leads to a measurable contribution to the profitability of a mill. In order to maximize the margins, controlled loops can be realized, allowing mills to run product parameters very close to the thresholds. With its control functions, the NIR multi online analyzer offers the option of lowering safety margins and responding more quickly to process fluctuations. With the simultaneous reduction laboratory analyses, costs for quality assurance are also optimized.

Seamless analysis and traceability

The NIR multi online analyzer enables a complete analysis of the most important product parameters for raw materials and in the ongoing production process for intermediate and finished products.

Another great advantage of this new online NIR generation is its increased industrial suitability. Only the measuring point is located in the production environment while the control room or MCC is offering an optimal environment for the optical and electronic components. The compact measuring points are well suited for upgrade solutions in existing plants.

But there are also revolutionary technologies entering the milling process. The recently launched online particle size measuring system, MYTA, is applied for continuous particle size measurement within a range of 10 to 5,000 microns. This allows the monitoring of intermediate and end products in cereal processing.

Whether in the different breaking and refining passages of a wheat mill or by monitoring material being ground on other devices, the exact registration of the granulation is crucial for the quality and consistency of the end product.

The fineness of flour and semolina has a substantial impact on the water absorption capability and a wide range of rheological characteristics of the dough in the downstream processes.

Bühler’s online Particle Size Measurement (PSM) provides this information, including traceability, on the basis of its online particle size measurement and monitoring technology.

The sampling stream for the online particle size measurements is led into a bypass. The integrated sampler draws a representative product amount and feeds it continuously to the sensor. The optical measurement results are continuously calculated and transmitted to the associated computer where the transformation into mass percentage is done. For intelligent loops, this information can also be transmitted to the process control system. All results are displayed and archived in the form of trend graphs as well as numerical particle size distributions.

Online PSM is already in use in the following applications in various grain mills:

Online wheat flour monitoring: It grants continuous quality assurance; an alarm message is issued in the event of oversized particles, e.g. due to a screen damage.
Online durum semolina monitoring: For a continuous monitoring of the granulation, an alarm message is issued in the case of a granulation drift-away from the target value.
Online break passage monitoring: Real-time surveillance of the performance of the first and second break. The operator is advised if the performance is out of tolerance.
Monitoring of the particle size distribution and compositions of milling products is merely an initial application. Bühler is already working on the next step in these innovative technologies, aiming to make the data available for Intelligent Process Optimization (IPO) applications. This would enable the automatic setting of the grinding gap of roller mills and influential recording of other devices. Based on closed-loop control circuits, operators will have more time available for peripheral duties.