Continous bleaching in palm oil production

The bleaching process changes the light brown CPO colour to an attractive golden yellow colour. The degummed CPO oil is first steam heated to 120 – 130°C and mixed with phosphoric acid once again: it runs first through the acid mixer and degumming tank. The oil is then pumped into the bleacher where it is mixed with bleaching earth, also known as Fuller’s earth. This is a clay material that has the capability to decolourize oil or other liquids, without using aggressive chemical agents. The bleaching earth is able to remove and absorb the impurities and other unwanted matter, such as colouring substances (carotenoids), soaps and proteins, which can be found in oils and fats. The process takes place under vacuum conditions in the bleacher tank. Process variables such as moisture levels, temperature, contact time and vacuum are important parameters in the oil purification process, to achieve a high quality refined oil product. Inside, sparging steam is used to obtain a homogenous mixture. The oil leaves the bleacher and is then filtered. The purpose of filtration is to remove the spent chemicals. The clay is filtered either on Plate Type Filter Presses or on Vertical Pressure Leaf Filters.

KROHNE offers different instruments for flow, temperature, level and pressure measurement. The OPTIWAVE 5400 is a 24 GHz FMCW radar level transmitter: this is designed for measuring liquid levels in difficult environments – for example in tanks with agitators, even containing corrosive liquids. The patented empty tank spectrum function eliminates false reflections caused by tank internals – for example rotating agitators. The OPTIBAR DP 7060 Differential pressure transmitter has an extremely compact measuring cell, and has a robust and precise response to temperature changes and with step response times of just 125ms, it provides enough measurements for reliable and stable process control. For a robust and accurate differential pressure measurement, even under changing process conditions, each OPTIBAR DP 7060 DP transmitter is linearised in 3 dimensions during calibration: differential pressure, ambient temperature and static pressure are taken into account in combination.