1 Carbo Solutions InternationalGood Sugar Manufacturing Practice Theo H de Beer Carbo Solutions International

2 2 Abstract Good manufacturing practice are steps taken to ensure maximum profitability and minimum losses in the factory operation. The subject is vast, but three of the more pertinent points that is required for operating an efficient sugar refinery or raw house will be touched on very briefly in this presentation. It is not rocket science and without going into too much detail, it is basically only the application of common sense that is required

3 3 Introduction Get the sugar out as soon as possible. Minimise or where possible prevent recycling Put into place measures & checks “If you cannot measure it, you cannot manage it” Get plant & equipment to do what it was originally designed and intended to do, “back to basics”

4 4 Introduction Before expanding on these, it is necessary to understand some of the fundamental effects in the process that if overlooked, it will result in sucrose destruction, hence losses and which can cost the factory a substantial amount in revenue

5 Introduction At Low pH Sucrose inverts5 Introduction At Low pH Sucrose inverts It chemically breaks down and is no available for recovery and it is thus lost. longer At high temperature Sucrose also breaks down and also will be lost as above. Extended retention will give the forces of inversion time to invert more sugar and further push up the losses

6 6 Low pH At low pH and elevated temperatures sugar hydrolyses into invert sugar. Sucrose breaks down to form glucose and fructose which is not available for recovery and will therefore be lost – it will be reported as “undetermined loss” C12H22O5 Sucrose + H2O + Water C6H12O6 Glucose + C6H12O6 + Fructose

7 Rate of inversion % Sucrose Inversion hr-1 at 100 % Inversion pH7 Rate of inversion % Sucrose Inversion hr-1 at 100 oC & at Various pH Values 6 5 4 3 2 1 % Inversion 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 7.9 pH

8 Taking the Rate of Inversion atRate of Sugar Solution Inversion at Elevated Temperatures 8 1600 1400 1200 Percent Inversion Taking the Rate of Inversion at 100oC to be 100% 1000 800 600 400 200 Temperature oC 25 40 45 50 55 60 65 70 75 80 85 90 95 100 105 107 110 115 120 125 130

9 Different Temperatures and pH% Sucrose Inversion / hour at Different Temperatures and pH 9 5 % Inversion per hour 4 Temperature 0C 50 80 100 110 60 90 105 120 70 95 107 3 2 1 .6 6.8 pH

10 Vukov’s Formula Modified10 Vukov’s Formula Modified Based on a paper by Vukov published in the International Sugar Journal of titled “Kinetic aspects of sucrose hydrolysis” the effects of temperature, pH and retention can be quantified.

11 Vukov’s Formula Modified11 Vukov’s Formula Modified F G H I J L M N O P Q R T U Retention vessel (m3) Retention (minutes) Operating Temp pH Density temp Flow Rate (m3 hr-1) corrected oC pH (Brix Corrected) dpH/dT Operating pH VUKOV (Log (K) (K) % Loss Ton Sucrose exposed / hour Sucrose inverted (hour-1) 5.56 -3.0E-03 5.41 -5.11 7.8E-06 0.039 6.34 0.0024 B C D E Ton Brix per hour Ton per hour Brix % Purity 20.0 Density temperature correction =0.998+( *Brix)+( *Brix 2) pH corrected for Brix =pH-(0.014*(Brix/2)) dpH/dT = (0.015*corrected pH)-(0.0017*(pH Brix corrected2)) Operating pH =((Temperature – 25) *(dpH/dT)+(pH Brix corrected) Vukov (Log K) =16.91+LOG(Density temp corrected*(1-(Brix/100)))- (5670/(273+Operaring temp))-Operating pH

12 Brix % Purity pH (hour-1) (Week-1) 75 6.0 85 6.5 65 8.0 7.0 5.012 Ton Brix per hour Brix % Purity Ton per hour Flow Rate (m3 hr-1) Retention vessel (m3) Retention (mins) Operating Temp oC pH Ton Sucrose exposed / hour Sucrose inverted (hour-1) Ton Sucrose inverted (Week-1) 20.0 63.0 99.9 31.7 24.4 49.3 75 6.0 6.34 0.0024 0.37 15.0 36.9 0.0018 0.27 10.0 24.6 0.0012 0.18 85 6.5 0.0025 0.0008 0.11 65 0.0002 0.03 8.0 0.0001 0.01 7.0 0.0003 0.05 5.0 0.0142 2.13 67.0 29.9 22.5 40.0 5.96 0.0007 0.1108 63.5 31.5 24.1 37.3 6.29 0.1139 60.0 33.3 25.9 34.7 6.66 0.1161 0.1143 98.0 6.22 0.1121 97.0 6.16 0.1110

13 – Keep temperatures down where possibleSucrose Inversion 13 It is therefore important to control the pH in the process. Run as close to neutral as possible – Keep temperatures down where possible – Minimise retention, or run at as high a throughput as possible. Where equipment is run in parallel, when throughput drops, try and take equipment off line and park them off, rather than slowing the operation of that plant

14 14 Sucrose Inversion Even in the best run factory, chemical breakdown is inevitable and it can be expected to be in the order of about 1.5% of the sugar input in a raw house This is made up approximately : 0.3% lost between juice massing and clarifier outlet 0.5% lost across the evaporators 0.7% lost between pans & final sugar massed out

15 Typical Undetermined Loss Profile15 Typical Undetermined Loss Profile % Undetermined Loss 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.7 0.6 0.5 0.3

16 16 Sucrose Losses This means sugar recycled, will be exposed to chemical breakdown each time it is recycled. Sugar returned to mixed juice tank will be exposed to the 1.5% loss twice, its loss will therefore be 3% Sugar returned to syrup is exposed to = 2.2% undetermined loss instead of the usual 1.5% Loss.

17 Get the sugar out as soon as possible17 Sucrose Losses As a guide, if it is necessary to recycle sugar, return it back as far down the process as is possible. Try and send it back to product of a similar purity. But the ultimate aim should always still be refrain from recycling. Get the sugar out as soon as possible

18 18 Sucrose Losses These losses due to recycling applies not only to crystalline sugar, but also to spillages during the process and to excess washing in the centrifugal which will dissolve sugar and will then be recycled At 85oC 20 g water dissolve 80 g sugar (1:4)

19 Sucrose Losses Spillages, leaks & glands passing are avoidable.19 Sucrose Losses Spillages, leaks & glands passing are avoidable. But if they do occur, clean up immediately, before microbial degradation sets in. Repair leaking glands, pipes, tanks etc immediately. So often it is perceived that if spillages are recovered it does not matter. This is totally false. If the spill is recycled it will incur loses. If it is left unattended to, microbial activity will set in and drop the pH and invert sucrose

20 Sucrose Inversion losses20 Sucrose Inversion losses Undet loss Sucrose Loss Mol loss pH Temp Time More molasses Increase loss in molasses Sucrose Reducing Sugar Microbial degradation Melassegenic & Physical Higher viscosities Loss in crystallisation & fugal wash & recycle

21 21 Sucrose Losses Taking a practical look at a few areas in the operations where sucrose degradation often take place and thereby push up losses. These will briefly be discussed.

22 Mud levels in Clarifiers22 Mud levels in Clarifiers Multi tray (Rappi Dorr units) Table on left is actual mud levels seen at a mill Sucrose Loss in Clarifier In Overflow (Clear Juice) & in Underflow (Mud) at 50 45 40 35 30 25 20 15 10 5 Different Mud Levels) T Sucrose Lost in Mud / Week Get mud out Do not build up mud levels in the vessel Ton Sucrose Inverted in Mud (per week) Ton Sucrose Inverted in Clarifier Juice (per week) 1 2 Le 3 l at ve 4 5 Which M 6 perated at 7 8 ud is O

23 Effect of Velocity on HTC23 Effect of Velocity on HTC Heat Transfer Coefficient 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.35 Velocity of juice flow inside tube 2.79 Low velocity results in Low HTC this means exposed to heat for longer & high localised heating

24 Measurement and Control24 Measurement and Control Put into place measures and checks “If you cannot measure it, you cannot manage it” This is not always appreciated and often viewed only as a nuisance with no benefit

25 Measurement and Control25 Measurement and Control It is important to put into place regular mass balances to calculate recoveries and losses at least on a weekly basis. With the advent of technology this can be done far more regularly, much easier Have laboratory results displayed in the plant for the operators to see and so that they can make the necessary adjustments to rectify problems Make them available to all concerned

26 Measurement and Control26 Measurement and Control Check lists should cover daily routine operations, schedule stop-day work and maintenance jobs. List the required jobs, delegate individuals to carry out the job. They must then fill out the check sheet, sign it off, thereby verifying the state of the job & take responsibility that the job was carried out correctly . Lists must then be scrutinise by the supervisor and or manager who must then check a few jobs and be satisfied the work was done satisfactorily.

27 A Typical example of a check list27 A Typical example of a check list No STOP DAY CHECKLIST SIGN 1. Check flash tank level trips 2. Liquidate flash tank 3. Empty out MJ heaters 4. Clean and wash pH pot 5. Pump water through Rotameters 6. Pump water through lime pump & pipes 7. Keep 3 containers Biocide at Clarifiers ( For use during day) 8. Wash out CJ sample tubes 9. Empty &wash lime tank (Diffuser supply)

28 A Typical example of a check list28 A Typical example of a check list No STOPDAY CHECKLIST SIGN 1. Dose biocide 10 ℓ in each Clarifier 2. Open flash tank manhole door 3. Open surge tank manhole door 4. Wash mixed juice scales: Top & bottom 5. Wash surge tank 6. Wash flash tank until clean

29 A Typical example of a check list29 A Typical example of a check list No STOPDAY CHECKLIST SIGN 1. Mix flocculant (12h00) 2. Inspect surge tank and box up 3. Inspect flash tank and box up 4. Assist evaporator attendant (14h00- 16h00 shift) 5. Prepare for start up (16h00-18h00 shift) 6. Clean Clarifier inlet boxes:-

30 Developed check sheets for each job.30 Check sheets must be allocated for all sections covering all duties of the different shifts, for both routine operations and for scheduled stop work and for maintenance work. Developed check sheets for each job. CLARIFIER ATTENDANT: EVAPORATOR ATTENDANT OLIVER FILTER ATTENDANT PUMP ATTENDANT A PAN BOILERS B/C PAN BOILERS CENTRIFUGAL SUPERVISOR FINAL INSPECTION, before boxing up

31 Measurement and Control31 Measurement and Control Follow up and repeatedly inspect This is always a very important role and can save plenty of time A leaking manhole gasket on a 1st effect evaporator once steam lines are pressurised will delay start up for a few hours, as the steam pressure has to be lowered again and the vessel cooled before access is possible to rectify the problem if it was not checked

32 Measurement and Control32 Measurement and Control It is of utmost importance that communication between departments are good Production, Engineering/maintenance Warehousing Packaging Each is a provider and each has a customer down stream. Treat them accordingly Communications between shifts at shift change

33 footprints throughout the factory33 Inspect rather than Expect This is very important There should be evidence of people’s footprints throughout the factory

34 Move around, inspect rather than expect34 Mr Manager Foreman Operator Move around, inspect rather than expect Technician Planning, Quality Electricians,mechanics

35 35 Laboratory The laboratory plays a vital role in operations. It is a vast subject on its own but it is good to look at a few important points and discuss these briefly. After all this is the place most measuring is initiated from. Operators must be confident of the figures they are expected to react on, so it is in their interest to keep in close liaison with the quality control department - For the benefit of both operations & quality control.

36 Laboratory Results are only as good as the sample is36 Laboratory Results are only as good as the sample is In the interest of all concerned and to ensure laboratory results truly represent the product: Ensure: •Samples are representative. Wash clean & dry receptacles, or rinse with product •Sample is not contaminated or evaporates. •Keep receptacles closed •Cool if possible

37 Cooling jacket with Chilled water Passing through37 Mixed Juice Sampler / Cooler Juice Flow Warm water out Return to chiller Chilled water in Cooling jacket with Chilled water Passing through Depending on cane payment method this can be an important test & all possible precautions must be taken

38 Sampling Molasses / Run Off from a delivery line38 Sampling Molasses / Run Off from a delivery line A Because the line cools & at times choke when the sample valve is throttled to prevent sample container overflowing, put in a by-pass line and run this and tap off this hot circulating stream with a short stub. Valve A fully open Valve B throttled to fill bucket 3/4 over the sample period B A B

39 39 Syrup sampler. Adjust sample rate to get the sample bucket about ¾ full at the end of the sample period

40 sampling falling sugar in a40 One of many sugar Samplers sampling falling sugar in a closed pipe. Cylinder driving piston Timer Sample Container

41 With sugar different grain sizes separate on the belt41 Rifflers for sub-sampling products like Sugar & Suspended solids in juice If analyse suspended solids in juice, which has floaters & sinkers. Pouring off the sample, even after it is well stirred, floaters will come off & sinkers remain behind. With sugar different grain sizes separate on the belt

42 Display hourly results for all to see 42 Display hourly results for all to see Visual displays are often simpler to understand than figures It also keeps the following shift informed of the current situation Mechanical / Electrical can make adjustments Marketing knows what is available Management is informed of the situation

43 43 This could raise questions or initiate investigations as to why is the quality is varying from one hour to the next?”

44 Or often the affect of defects are not appreciated44 It is not uncommon for people to modify equipment without really knowing the basic principles and end up changing what has been developed by the supplier over a period and after plenty of research and development Or often the affect of defects are not appreciated

45 At RH 100%, there is no evaporation, hence no cooling is achieved 45 In the centre RH is 100% Would have been better to extend length Effectiveness of spray pond depends on the atmospheric RH (Relative humidity) At RH 100%, there is no evaporation, hence no cooling is achieved This spray pond expansion would have been better to extend length wise rather than making it wider . Double layer spray also no good

46 The extent to which some people go to keep 46 The extent to which some people go to keep suspended solids levels down in sugar. Filter air intake when the pan breaks vacuum It would be better to break vacuum with steam Magnet in pan feed – use Stainless steel piping Prevent rather than cure

47 This will be an additional 4.5 liter wash water 47 Taking a 1750 “A” centrifugal (Charge 1750 lt) If wash water is increased by 2 seconds This will be an additional 4.5 liter wash water This water can dissolve 18 kg sugar Sugar that will be recycled and reworked Taking a 250 TCH factory (5400 TCD) This will be ton sugar recycled / annum Taking a conservative figure of US$ 15 as the cost of reworking the sugar (Ops and energy) Recycling will cost $60 000

48 Not only is it rework cost, there will also be 48 Not only is it rework cost, there will also be chemical loss when recycling the sugar. The dissolved sugar will end up in the run off and increase run off purity which will drop the exhaustion It can be shown that 2 second extra wash will drop exhaustion by 1.44 units Since 1 unit exhaustion will elevate the UDL (Undetermined loss) by 0.035% 1.44 units exhaustion ≡ 0.05 increase in UDL

49 There is a correct and an incorrect way to fit the screens49 There is a correct and an incorrect way to fit the screens It does not look like a serious dent, but take a closer look

50 50 Some factories renew C centrifugal screens routinely every 4 to 6 weeks, cascade the old C screen to B duty

51 51 Drip gates passing raises sugar colour & the first reaction of the operator is to add more water This will dissolve sugar which effectively will have to be recycled (Increase undetermined loss)

52 Look for tell tale signs in the operation.52 Look for tell tale signs in the operation. Typically the pattern on the sugar face in a centrifugal basket can indicate possible problems

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56 Need a good clean screen after ploughing out the sugar.Any sugar remaining on the centrifugal screen is dissolved & recycled with basket wash 56

57 Close to 20 mm sugar left on this basket57 Not like this. Close to 20 mm sugar left on this basket (One machine like this will recycle nearly 40 ton sugar a day)

58 Effect of poor ploughing & leaving sugar in basket after ploughing. 1 58 Effect of poor ploughing & leaving sugar in basket after ploughing. Based on a K 1750 batch BMA. (Basket  1540 & ht 1170 Charge 1750kg) Depth of sugar left on basket after ploughing (mm) 1 2 4 10 20 Sugar left on Basket (kg) 4.7 9.4 18.8 46.7 92.8 Kg Sugar Recycled / day (24 hrs and 18 cycles / hr 2,029 4,056 8,101 20,176 40,099

59 between for the runoff to purge through59 Need good square regular grain with voids between for the runoff to purge through

60 As mentioned before, even the best reclaim 60 As mentioned before, even the best reclaim implementation will not reclaim every bit from spills. Some sugar will be physically lost to drain Some sucrose will get lost through degradation

61 61     Not the best entrainment drain

62 Some basic problems that can do with62 Some basic problems that can do with attention

63 63 Conclusion Good manufacturing practice is simply decisions taken in reducing sugar losses. good We have discussed a few examples of options that can be taken to reduce sugar losses. The effort taken to systemise good manufacturing practice can have significant financial returns Management support from the top is imperative to keep such initiatives from loosing focus.

64 THANK YOU FOR YOUR ATTENTION!