Robert W Howe BetaVA Ltd Background 2 nd carb filtration at British Sugar Wissington sugar factory had become a process bottleneck Largely due to Insufficient filtration area for the budgeted factory throughput ID: 1041513
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1. Development of the Putsch Segment FilterRobert W. HoweBetaVA Ltd.
2. Background2nd carb filtration at British Sugar Wissington sugar factory had become a process bottleneckLargely due to Insufficient filtration area for the budgeted factory throughputPoor beet cleaning, too much clay and flume water entering the processMuch improved following the installation of Putsch Jet Wash Roller TablesSome due to Excessive alkali addition from NRS softening regenerant depressing 2nd Carb particle sizeA satisfactory workaround had been developed for regenerant handlingOccasional poor Carb control and operator knowledge/ decision making Poor slice quality Improvement through working with Putsch on knife sharpening, slicer block cleaning and settingLost opportunity when filter off for acid clean or bag change
3. Wissington use Dorr juice purification Overall this delivers good 1st Carb filtration & acceptable 2nd Carb filtration but poorer juice quality Purification system is stretched, clarification and post reaction tanks undersizedColloidal (clays) material not precipitated as they are in classical purification The colloidal material suppresses particle size in 2nd Carb and also leads to post precipitation and filter bag scalingIn 1993 Wissington installed 5 x 2.8m Ø Gaudfrin Diastar filters Station designed on 1.2 m3/m2/hr because of the juice purification system60 x 2 x 0.75m elements per filter890m2 for a beet slice of 14,000tpd - 6.35m2/ 100T BS As factory capacity increased, throughput lost opportunity was a common occurrenceOver 25 years the throughput increase at the factory had seen the installed 2nd Carb filtration area reduce to 4.8m2/ 100T BS Juice quality and filterability needed to be excellent, filtration values of 3-6 secs (250ml)Filter performance managed with copious acid washingBackground
4. How much Filtration Area do I need?It was often said in British Sugar “You will never regret putting in the most area you can get!” However when filtration is poor you will never have enough area!!From the benchmarking carried out, Wissington’s installed 2nd Carb filtration area was lowBenchmarking would postulate the minimum area for the various types of juice purification are:Minimum AreaDorr PurificationBMA 65 PurificationClassical Purification 2nd Carb Filtration Area8m2/ 100T BS 6.5m2/ 100T BS 5m2/ 100T BS
5. 2nd Carb Filter ProjectIn 2009 it was learnt Gaudfrin had developed a new double star Diastar designFor same diameter vessel 306m2 per filter or 1530m2 total, giving 8.27m2/ 100T BS Due to better filtration years/ reduced lost opportunity no further action had been taken Initially considered retrofit of Gaudfrin new double star but the existing vesselsWere approaching end of lifeCouldn’t accept the 3m long filter elements Looked to identify alternatives to double star DiastarPutsch had been developing an alternative filtration solution for such a dutyA new concept of a “segment filter”Pilot trial works had already commenced in Germany, no installations had been madePutsch invited to look at a solution for increasing filtration area within existing footprint Complimentary to the customer/ supplier relationship in place
6. In developing the segment filter concept, Putsch were looking to:Offer a candle filter with high performance to the sugar industryCombine the advantages of both candle and frame filters Meeting the requirements for improved filtration, throughput and quality Offer a 6 segment design for juice turbidity control and ease of handlingProvide the largest filtration area possible for each tank designFlatter Filter element design to increase filtration area Quick, easy & safe complete or partial exchange of elements Using pre-assembled segmentsPresent a well-developed state-of-the-art filtration optionSegment Filter Concept
7. Segment Filter Development
8. Construction of a pilot plant for a segment filterModification of a Sibomat vessel allowing a model of a segment filter to fit inInitial testing as a 1st Carb filter?Concept Testing - Pilot Plant #1
9. Test Filter cloth for Pilot Plant #1Cleaned ClothFilter CakeFilter ClothBackflushing
10. Concept Testing - Pilot Plant #2Pilot plant for sugar factory testing Containing two full size filter elements Initial testing at Offstein, GermanyAverage Filtrate flow rate of 1.6 m³/m²/hrAverage Filtration pressure of 1barAverage Mud juice concentration of 1207 kg/ m³2ppm Filtrate solid content Good filter cloth cleaning and clamp sealing
11. Building Confidence in a Segment Filter SolutionTo gain further confidence in the segment filter application at Wissington further trial work was done in 2017/18, becauseDorr purification systemFiltration had become such a significant issue at the factory any proposed change needed to be rightPutsch test rig installed and a sampling and performance testing protocol established
12. Wissington Factory Trials1. Wissington ran a half a Campaign of trials completed with pilot plant rig to get confidence2. Filtration cycles achieved >60mins with 1bar pressure4. Nominal clarity 10ppm vs 19ppm ex Gaudfrin on the same feed & 39ppm suspended solids ex Gaudfrin in 2016/17 Campaign 3. Mud densities achieved 250g/lüüü5. The achieved flux rate exceeds the guaranteed flux rate of 1.2m3/m2/h from Putsch. The only dip below was when filter bag was tested to end of lifeüGFO – Gaudfrin OutletPTR – Putsch Test Rigü
13. Wissington Factory Trials6. The density of the mud dump is above the Putsch guarantee of 250g/l. Converting the data below, 1.17sg equates to ~310g/l. This was higher than the current installation and should lead to a lower level of internal factory recycle7. The Pre-Filtration volume was set to ensure clear filtrate of suitable quality throughout the cycle. As a result the cycle efficiency (total volume filtered vs total cycle volume) matched the current installationüü
14. Test Rig achieved Putsch guarantees on Wissington 2nd Carb JuiceFlux rate of at least 1.2 m³/m²/hr achieved on clean filter cloth Typically between 1.4 and 1.6 m³/m²/hr Filter could operate at 1.4 bar feed pressure Pressure difference between inlet and outlet Mud concentration of > 250 g/l was achievedA clear filtrate quality of 10 ppm suspended solids achieved (20ppm max)A number of improvements were identified and recommendedSummary of Factory Trials
15. Lower connectorEach element is 2.5m in length Filter cloth pulled over frame and sealed by a two piece clamp“Double Bridge“ support screen provides excellent drainage Filter ElementFilter BagUpper connectorSealing ringThreaded tie rod and anchor boltSegment LocatorDouble bridged Support Screen
16. Filter Element DevelopmentWorked with Putsch to improve connector design for bag sealing and for smooth edges to frame to prevent bag tearing when being changed
17. Filter Cloth MountingFilter cloth pulled over the filter candle and the lower connectorThe open end of the filter cloth is folded back over into the lower connectorThe upper connector than is placed on top of the lower connector This clamps the filter cloth tightlyThe anchor bolt of the candle is inserted from below into the opening in the segment The candle is secured with a nut and tightened to a given torqueThe filter cloth is correctly clamped and sealed to the segment
18. Each filter has six segmentsFor the 2.9m diameter availableEach segment has 45 elements per segmentTotal of 270 elements per filter340m2 per filter or 1,700 m2 for the 5 filters, almost doubling the previous filtration area!!Filter Segment
19. Filter lids can be placed on top of each other to save spaceInstalled Segment FiltersMild steel vesselsOptional internal acid resistant coating to allow acid washingFilter segments sit on 3 support points in the vesselThe three guide tubes pass through the positioning bores
20. Installed BenefitsThrough the innovative segment filter approachIn 2018 Diastars replaced 1:1Much piping re-usedWissington installed 1700m2 = 9.19m2/ 100T BS 91% more area than previous within same footprint Head tanks for backwashPressurised pumped systems also availableFuture proofed capacity increase at Wissington Segment isolation on solids breakthrough 1 segment isolation allows filter to run at 83% capacity!Rapid filter bag change In a few hours c/w 24hrs previouslySafety - No filter entry for bag changeDesigned Filter element re-bagging areaPrevious Installation required vessel entry for bag changing- Bags removed individually - 3m fall as bags removed!!Rapid Filter bag change with no need for vessel entry
21. Lost OpportunityVirtually no lostOpportunity due to 2nd C Filtration evenIn a difficult filtrationyearLost OpportunityTonnes Slice per Campaign
22. Segment Filter OverviewCapital Efficiency - max filtration area per body diameter Ability to fit into existing footprintRobust high performanceFiltration rates (Flux) , clarity etc.Fast and reliable backflushEfficient removal of suspended solidsAdjustable thickening rate of mud concentratePartial filter isolation in the event of a breakthroughMinimal filter availability issuesSafe and fast exchange of filter elementsAbility to Clean in Place (acid washing)Easy to maintainRemote bag changingPotential for other sugar factory applications