In-line NIR – Turning low protein wheat into high

Artcile reproduced from FOSS, InFocus magazine by Nirperfomance editorial staff,

South African grain suppliers, Senwes have tried out a new way of using in-line NIR to optimize the use of increasingly-scarce high-protein wheat in blends going into milling, helping to get the very best out of both high and low protein material.

In the fairy tale of ‘Rumpelstiltskin’ a miller boasts to a king that his daughter can spin straw into gold.

While nothing can make this enduring dream come true, modern process analytical technology in the form of an in-line NIR analysis system is making a real difference to what millers can get out of wheat grain deliveries. It is not exactly turning straw into gold, but is perhaps the next best thing given the increasing scarcity of high quality wheat.

The new process analysis solution has been on trial at a Senwes facility in South Africa, consisting of an NIR analyser, a sample interface and special software for graphical display of the results.

It has been used at a group of silos next to a large mill. The different silos contain different minimum protein levels, 9%, 10%, 12% and so on. The sample interface is installed in a pipe that delivers grain from the different silos onto a conveyor belt that serves the mill. The sample interface is installed by cutting a hole of about 10 cm diameter in the pipe. It has a sapphire window that sits flush with the sides of the pipe allowing the NIR unit to take measurements on the grain as it flows by. The pipe is at an angle of about 75 degrees to ensure a smooth uninterrupted flow of grain.

Measurements are made every few seconds and the results are displayed on a computer in the control room where they can be viewed as a trend graph, making it very easy to keep track of the protein content. If for example, 11% protein is the target and the level starts to fall below, then a little higher protein wheat can be added to stabilize the protein content of the wheat.

Lower grade to higher grade

Manager of Special Products, Mariana Purnell describes how the NIR system was installed at the Senwes facility in October 2012. There is limited data available, but it can be seen already that good results have been achieved. In the graph below, the blue line shows the initial stock level with tons indicated on the Y axis and different gradings on the X axis, B1, B2 etc with B1 the highest protein content.

The NIR system enabled continuous monitoring of wheat protein levels to allow inline adjustment to regulate the blending and maintain specific protein levels during outloading. As indicated by the B1 – B3 columns, this resulted in all the lower grades being blended with higher protein grades, yieldingB1 and B3 grades considerably higher than the initial stock level. “We successfully managed the optimization of all protein levels and the homogeneity of quality in all wheat batches ,” says Purnell. “As far I am concerned the unit works very well for managing your grain quality as it monitors 100% of the batch being loaded and really keeps protein fluctuation within a narrow band.” She also points out that it is of course important to have the right quantities available to maximize the use of the in-line NIR system.When the system was brought into use there were just over five thousand tons of grade 1, about four thousand tons of B2 and four and a half thousand tons of B3 grade and lower amounts of lower grades.

“We can see that the level of control and management of the protein level being shipped out is far superior to when it is controlled by a human being who does infrequent sampling and testing,” says Purnell. “By gathering more precise data of protein units leaving the silo, one can be assured of a lower number of disputes related to protein levels and subsequent downgrading.

She reports how more and more farmers taking land out of wheat production in pursuit of more profitable crops. In recent years, amounts of the highest grade wheat have been falling while the lower grade wheat intake is growing. “We need to make the most of the high protein wheat that we get in,” says Purnell. “We feel that the upgrading can be optimized with the use of the NIR system and blending the grain as it goes through.”

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