MEBA
Pneumatic conveying systems are a major driver of energy cost and carbon emissions in grain milling. Bühler has developed a retrofit system that adapts in real time according to changes in pressure demand, cutting energy consumption by up to 30 percent. The new approach is a significant step toward more efficient, intelligent, and autonomous milling operations.
Jonathan Ward, June 2025
In modern milling operations, intermediate and finished products from the grinding process are transported by air. This pneumatic system is fast, flexible, hygienic, and highly automated. It allows mills to run continuously, maximizing output, and keeps dust contained for a safer and healthier working environment. These advantages are not cheap. Mill pneumatic conveying systems rely on large fans to generate the high negative pressures needed to move the material through the system. In a big mill, the high-pressure fan might be powered by a 150-kilowatt motor or larger. That makes the pneumatic system the second biggest standalone energy consumer in the grinding floor of a mill, after the roller mills that turn the grains into flour. In a typical mill section, the high-pressure fan is responsible for between 23 to 28 percent of total energy consumption.
In mill operations, as in other large-scale industrial processes, energy consumption has become a key target for efficiency improvement efforts. Historically high energy prices, especially for the electricity used to power rotating equipment, are driving up production costs and squeezing margins in a cost-sensitive commodity sector. Mill operators also face growing demands from governments and other stakeholders to monitor and reduce their energy consumption and associated carbon emissions.
Whether they want to reduce cost, carbon, or both, mill operators are increasingly searching for ways to cut energy consumption across their operations. The mill’s pneumatic system is a great place to start, says Javier Lozano Díaz, Product Manager, Automation & Digital Services, Milling Solutions at Bühler. “Traditionally, high-pressure fans in milling operations run at a constant speed, regardless of the actual demand,” he says. “The system does not adapt to fluctuating loads, nor does it reduce speed while in suspend. This leads to unnecessary energy consumption and inefficiencies.”
Now there is a better option. Díaz and the Milling engineering team at Bühler have developed a retrofit solution for mills that puts the pneumatic system under intelligent control. The High-Efficiency Retrofit for Mill Pneumatics requires only two additional components: a pressure sensor, which is normally installed just upstream of the dust filters at the end of the suction line, and an advanced variable speed drive and controller connected to the high-pressure fan motor.
In operation, the new system collects data in real time from the pressure sensor and uses a proprietary smart control to continually adjust the speed of the fan. This allows the pneumatic conveying system to operate at optimal efficiency as loads and production rates change.
The impact on energy consumption is immediate and significant. In tests at customer sites, installing the energy efficiency retrofit package can reduce the energy consumption of the high-pressure fan by 30 percent; on average by 20 percent. “Savings like that make a strong business case for this technology,” says Díaz. “The new system pays for itself in less than two years in most of the sites we have evaluated. Sometimes, payback can be less than a year.”
Running the pneumatic system at peak efficiency doesn’t just save energy. Slower rotating speeds reduce wear and tear on fans and motors, and lower air flow rates can help dust filters last longer.
The energy efficient retrofit package can be installed as a standalone system, connected to a plant-wide Energy Management System (EMS), or integrated with one of Bühler’s mill automation systems, such as WinCos or Mercury MES. Doing that creates extra improvement opportunities for operators, explains Díaz, allowing them to understand and optimize the impact of operational changes on energy consumption across their processes.
A holistic approach is key for any business seeking to reduce costs and energy consumption in industrial equipment, says Díaz. While the energy efficiency retrofit package provides a fast route to significant savings, there are plenty of other things mill operators can do to optimize their operations. “Implementing preventive maintenance helps to ensure equipment operates at peak efficiency,” he explains. “Operators can also look at upgrading power-hungry equipment with energy-efficient motors and drives or using digital monitoring solutions such as Bühler’s EMS to track and optimize energy consumption in real time.”
To help mill operators meet their energy efficiency ambitions, Bühler offers an energy audit service in which process experts review end-to-end mill operations to identify improvement options and calculate their relative costs and benefits.
Meanwhile, Bühler is constantly looking for new ways to help customers reduce energy consumption. “The pneumatic system usually contains the largest fan in a mill, but these facilities will have dozens of other fans scattered across their operations,” explains Díaz. “We are exploring opportunities to apply a similar smart control approach to these smaller units where it makes operational and financial sense to do so.”
Then there is the most energy-hungry process in milling, the roller mills at the core of the mill. “The Bühler SmartMill program is a journey to optimize yield, increase product quality, improve traceability, reduce energy consumption, and increase overall plant efficiency,” says Díaz. “Incorporating advanced sensors into mill equipment, including the rollers mills, helps us to understand the impact of material and process variability on energy consumption.” The ultimate vision for the program is the creation of mills that adapt continuously and autonomously to maintain peak performance.
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