Controlling Moisture in the Rapeseed Oil Extraction Process

Controlling Moisture in the Rapeseed Oil Extraction Process
Oil can be extracted from the seeds of many plants, including rapeseed, a widely cultivated plant that has become popular due to its beneficial health properties. Rapeseed oil is low in saturated fat, high in unsaturated fat, and contains antioxidants.

The need to measure the moisture content of rapeseed 

The rapeseed oil extraction process benefits from moisture control for several reasons: 

  • Optimising the oil extraction process 
  • Increased product control 
  • Reduction in waste and spoilt product 
  • Direct real-time control of drying processes 

The control of the moisture during all stages of the oil extraction process is vital to produce a final product that is suitable for its intended market. 

The benefits of installing microwave moisture measurement sensors 

  • Dryers can be used more efficiently, reducing energy costs 
  • Improved and consistent product 
  • Reduction of spoilt/wasted material 
  • Not affected by dust or colour 
  • Real-time automation of the drying process, avoiding the need for manual intervention 
  • Reduced process downtime 

Recommended installation 

You can install a moisture sensor at various stages during the oil extraction process: 

  • Raw material delivery to site 
  • After Conditioning 
  • Before/After drying 
  • After oil extraction 
  • Rapeseed meal 
Figure 1: Moisture Sensor Locations
Figure 1: Moisture Sensor Locations

Example installation 

In the following example, a sensor was installed at the output of the dryer, enabling the control system to adjust the temperature to control the final moisture content of the seeds that have been flaked and dried. 

A Hydronix Hydro-Mix HT sensor was mounted in the underside of a chain conveyor due to the high process material temperature of 120°C in this application, however a Hydronix Hydro-Mix XT sensor could be utilised if the temperature is below 60°C. 

The sensor was installed so that the sensing face was flush with the internal wall of the conveyor, enabling the chain to move material consistently over the sensor ceramic faceplate. 

Result after installing the sensors 

After installation, integration, and calibration, sensors measure the moisture levels of the materials to an accuracy of +/- 0.5%, enabling the production process to be precisely controlled. 

Real-time control of the dryer (as opposed to waiting for oven tests) ensures that the dryer is controlled continuously, resulting in increased energy efficiency. There is also a reduction in the substandard or wasted product caused by the time delay between periodic sampling and subsequent dryer adjustment. 

Hydro-Mix HT sensors 

Hydro-Mix HT sensors are constructed of stainless steel and have an abrasion-proof ceramic measuring faceplate. The sensor is designed to be installed flush-mounted with the surface of the mechanical material transport system allowing the material to flow freely over the measuring faceplate without causing any build-up. 

The Hydro-Mix HT has configurable parameters such as signal filtering and smoothing, which are designed to eliminate noise created by the metal screw and air voids. The sensor also features a choice of output options such as 0-20mA (0-10V), 4-20mA, USB, Ethernet, and RS485/232 and may be configured to output a moisture percentage value directly from the sensor. The Hydronix Hydro-Com software enables simple set-up and configuration of the sensor using a PC or laptop and USB connection. 


The inclusion of a microwave moisture measurement system into the existing process enables the control system to: 

  • achieve consistent quality products 
  • reduce the number of spoilt materials  
  • provide instant savings  
  • fast return on capital investment.  
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Hydronix is the world's leading manufacturer of digital microwave moisture measurement sensors.

Established in 1982, we have installed over 85,000 sensors across a wide range of industries in over 80 countries worldwide.