SUNFLOWER OIL REFINERY - PART II

Processes

Neutralisation

For the neutralisation process, the raw oil was first heated up to 90 ℃. The required temperature was achieved by using a heat exchanger. The heated solution was then mixed with 5 mol/dm3 of Sodium Hydroxide, thus removing the free fatty acids (FFA). The neutralised solution then passes through a centrifuge
in order to separate the soap from the oil. The soap is discharged and the oil is combined with a stream of de-mineralised water at 20℃. After, it passes through a second centrifuge which produces 2 streams: one stream of sodium hydroxide and water and the other one being oil. See appendix 1 for calculations.

Fig 1 - Heat Exchanger

Fig 2 - Neutralisation

Fig 3 - Centrifuges in Neutralisation Process

 Removal of colour compounds

The oil product from the previous process enters another reactor where it combines with Fullers Earth with a flow rate of 19.72 kg/hr. The water from the mixture is then extracted by a vacuum while the two feed (i.e. sunflower oil and fullers earths) are mixed and cooled to a temperature of 40 ℃. The product then passes to a filter which separates it into two streams one of which is the oil and the other is the residue (fullers earth, colour compounds and oil). See appendix II for calculations.

Fig 4 - Colour Removal

 Hydrogenation

A hydrogenation reactor was used to fully saturate 65% of the sunflower oil and partially saturate 35% of the oil. The oil mixed with Nickel catalyst at 0.49 kg/hr while it is being heated up to 175℃. As in the previous process, it then passes through a filter to separate the oil from the catalyst.

Fig 5 - Hydrogenation

De-odourisation

The final stage of the refining process is to de-odourise the oil. This is done by passing the oil into a first try heating it up to 200℃ using hot water which is reclycled between tray 1 and 5. The next step is to allow the oil to pass into the second tray which is heated up to 240℃using heating fluid. The oil is maintain at a constant temperature while passing through trays 3 and 4, where the odour compounds are vapourised and extracted. After this is done, it is passed to the fifth and final tray where it is cooled down to 215℃ using cool water coming from tray 1. Note that the change in Temperature in tray 1 and tray 5 is the same because is the the same water is used. Finally the oils is cool down further to 60℃ by a cooler.

Fig 6 - De-odourisation

Scheduling Of The Refining Process

It is very important to schedule all the processes in a refining plant because it helps the us to plan how long each reaction will take and how much products we can expect at the end of the day. Working towards a goal of 20’000tonnes of Sunflower Oil to be produced by the end of each year, it is necessary to calculate roughly the reaction time in each process so that the size of reaction vessels required can be worked out.
Apart from estimating roughly the time taken at each stage of the refining process, we also included the size of the reaction vessels that would be required by using a simple formula (for continuous stirred tank reactor):



This formula was used for the neutralisation process as it is a continuous process.

Actual Flow rates in the reactor
Oil : (0.977)(3.384)(1000) = 3306.168 kg hr−1
FFA : (0.015)(3.384)(1000) = 50.76 kg hr−1
CC : (0.005)(3.384)(1000) = 16.92 kg hr−1
OC : (0.003)(3.384)(1000) = 10.152 kg hr−1

Volumetric Flow rates
Oil : 3306.168/942 = 3.5097 m3 hr−1
FFA : 50.76/849 = 0.0599 m3 hr−1
CC : 16.92/942 = 0.0199 m3 hr−1
OC : 10.152/942 = 0.0119 m3 hr−1

Total volumetric flow rate: 3.6014 m3 hr−1
Volume of tank =(5/60) x 3.6014 = 0.300116 = 0.3 m3

Drying and colour removal
Volumetric flow rates
Oil:\frac{977}{942} \cdot 3.384=3.5092 m^3\ hr{-1}
CC:\frac{5}{850} \cdot 3.384=0.01989 m^3\ hr{-1}
OC:\frac{3}{850} \cdot 3.384=0.01149 m^3\ hr{-1}
H_2O: \frac{4.95}{1000} \cdot 3.384=0.01675 m^3\ hr{-1}

Total Volumetric flow rate of feed = 3.5577808 = 3.56 m^3\ hr{-1}

Volume of tank proposed: 4\ m^3

Time taken to fill up the tank: 54 mins
Time taken to empty the tank because of resistance of filtration system = 60 mins
Reaction time 50 mins

Hydrogenation
Volumetric flow rates
Oil:\frac{977}{942} \cdot 3.384=3.5092 m^3\ hr{-1}
CC and OC:\frac{4}{850} \cdot 3.384=0.0159 m^3\ hr{-1}
H_2O: \frac{0.98596}{1000} \cdot 3.384=0.00333657 m^3\ hr{-1}
Total volumetric flow rates of feed= 3.5284 = 3.53 m^3\ hr{-1}
Volume of tank proposed: 24 m^3

Time taken to fill up tank: 407.93 mins = 408 mins
Time taken to empty the tank because of resistance of filtration system = 60 mins.
In the hydrogenation process the tank takes about 408 minutes to fill up. To calculate the resistance of the filter on this tank, a ratio of the filling up time and filtering time was taken from the drying and colour removal stage (10:9). Therefore the time taken to empy the hydrgenation time is 454 minutes.
Reaction time 400 mins

After a detailed analysis of the processes, the timing for each process in the different production stages was calculated. In total the first batch of refined sunflower oil can be obtained in 24 hours and 17 minutes. After this time the production will be continuous. The operating time of the plant is 6,000 hours per year. With timing calculated, the refinery plant is able to meet the target of 20,000 tones per year.


Link to:
SUNFLOWER OIL REFINERY-PART I, Click HERE
SUNFLOWER OIL REFINERY PART III Click HERE