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THE HOWDEN THOMASSEN FFP™ Oil-FEE AND viTuAlly FicTiON-FEE: THE PiSTON THAT FlOWS ON A FilM OF POcESS gAS
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h hw hm F FOT PTO HO O Ob H THOO, TH O b 17 OT O OTT PTTO FO OTO THT PH TH bO OF bT FF. p f mp Our products underpin many o the world’s most critical industries including power generation, petrochemicals and manuacturing, and include a comprehensive range o reciprocating process compressors or industries like oil, gas, chemicals and refning. The Free Floating Piston is a unique development in compressor technology that uses a cushion o pressurised process gas to oat the piston, virtually removing rider ring wear at a stroke. In the traditional choice between lubricated and non-lubricated systems, the solution to one problem oten become the cause o another:
Lubricated cylinders
on-lubricated cylinders
Oil consumption.
o oil consumption.
Tendency or valve plates to stick.
o sticking, longer valve lie.
uricant volume is adjusted to maximise compressor capacity, which means that oil concentration in the process gas increases at part load conditions.
o luricant.
To prevent contamination o the process gas, oil must e separated and drained.
o draining o oil required.
To prevent contamination o equipment, coolers must e cleaned regularly.
o oil contamination.
rained oil must e transported and disposed o, with environmental consequences.
o oil to dispose o.
ylinder lurication system requires regular maintenance.
o cylinder lurication system to maintain.
hw wk ^ vLL f-f pp s it travels in the cylinder, the FFP™ is carried y a thin cushion o process gas. hile the concept is simple, the implementation demands the highest standards o precision engineering.
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Pressure-sensitive valves have een added to the ace o the piston. uring the compression stroke, these valves are pushed open to allow the interior o the piston to ood with process gas under high pressure. The gas is then orced out through ow nozzles integrated into the ottom o the rider rings to orm a flm o pressurised gas, around 10–50 microns deep, that supports the weight o the piston.
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The lower surace o the rider rings carr y a machined profle that ensures the gas is distriuted accurately to create a earing layer, and the rider rings have een relocated to sit etween the piston rings, which thus orm a sealed enclosure. ontact etween the rider ring and the cylinder lining is eectively reduced to zero, and as long as there is pressure in the system the cushion layer is maintained, providing a ail-sae mechanism in the event o prolems arising elsewhere.
Special designed non return valves
L p h m f m s process requirements ecome ever more critical and environmental constraints more stringent, oil-ree compressor cylinders are ecoming increasingly prevalent. ithout lurication, however, conditions within the cylinder can accelerate the wear so drastically that running time etween maintenance stops may e reduced to a ew hundred hours. t the same time, commercial pressures increasingly demand uninterrupted running o three years or more. Our engineers undertook a radical rethink o the undamental principles o compressor design, investigating the principles and possiilities o each component. The outcome, the FFP™ is an elegant and ingenious method o virtually eliminating rider ring wear. t uses pressurised process gas to provide a cushion that li ts the piston clear o the cylinder lining, so that the rider ring is only in contact with the cylinder during the rie start up and shut down periods. The volume o gas required is extremely small – less than o ne per cent o the cylinder capacity – and compensated or in the cylinder design, so there is no loss o overall capacit y.
fow nozzles
The FFP™ rings all the advantages o oil-ree operation without the usual drawacks, while avoiding the expensive and time-consuming complications introduced y o lurication systems. t already has mo re than ten years proven perormance in some o the most demanding industrial situations. L h qkL p vm ter successully completing a rigorous series o in-house static and dynamic prototype testing, we worked in partnership with a cus tomer to pilot the system on-site in a heavy duty hydrogen compressor. This frst installation has now een running without prolems, with only minimal reaks or planned maintenance, since 1998. lmost 250 FFP™ systems have een installed to date, and the data accumulated over ten years o industrial experience shows that rider ring wear is reduced to practically zero, repairs are minimal and reliaility is excellent.
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PSSI CPSSI Howden Thomassen compressors Bv s a eadn nternatona spper o nnoate, hh-qat ompresson eqpment to the word’s most ta proess ndstres. Sne 2011, t has been part o the oba Howden oransaton, the word’s eadn spper o ans, ompressors, bowers and rotar reenerate heat exhaners. eonsed and respeted or eadn ede desn and the hhest standards o enneern, Howden has ompanes based n 17 ontres, ombnn a oa ee o sere wth aess to word-ass expertse and nraed experene. Eerthn we manatre s baked b a etme ommtment to spares, atermarket seres and ade on prades and retrots.
you would like to know more aout the Free Floating Piston, or investigate the cost enefts it might ring to your own ins tallatio n, please co ntact:
hoden oassen oressors Havelandseweg 8-a PO bO 99 6990 b heden The etherlands Tel: + 31 (0) 26 4975200 Fax: + 31 (0) 26 4975201 e: .toassen.co
Howden Thomassen Compressors BV is a memer o the Howden roup o companies.
©Howden grop lmted. A rhts resered. 2012 Howden and the fn H oo are restered trade marks beonn to Howden grop lmted.
