Product category:
Pumps, Vacuum pumps
News Release from: AxFlow | Subject: WCB pumps on biodiesel
Edited by the Processingtalk Editorial
Team on 24 January 2008
Waukesha Cherry-Burrell pumps for
biodiesel
In the processing of biodiesel from tallow and used cooking oils, certain stages can be fairly demanding for pumping equipment, but Waukesha Cherry-Burrell pumps have been trouble-free
During certain stages of the production cycle of biodiesel the semi-processed media can prove to be problematical: the possibility of the transfer pumps becoming clogged up is a constant threat At the Argent Energy plant in Scotland, AxFlow UK has introduced Waukesha Cherry-Burrell Universal II Series pumps for handling Glycerine-Like Product (GLP) and Bio Fuel Oil (BFO), this being the residue of the raw Fatty Acid Methyl Esters (FAME) produced by the distillation process
This article was originally published on Processingtalk on 2 Nov 2004 at 8.00am (UK)
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The Argent Energy plant in Scotland, which is now recognised as Europe's largest biodiesel processing plant has a capability to produce 45,000 tons of biodiesel per year.
The basic raw materials used are tallow and used cooking oils: the total production cycle from intake to finished product takes 24 hours.
With production being on a 24/7 basis, processing equipment is subjected to a very high workload and therefore must be capable of offering high levels of efficiency and minimum downtime.
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The AxFlow WCB Universal II rotary positive displacement pumps meet both requirements, and since their commissioning in 2006 they have been reported as having given trouble-free performance and far higher levels of operating efficiency than the pumps which they replaced.
Argent reports that the original pumps installed when the plant was commissioned required frequent cleaning of the rotors as they became blocked up.
This is primarily because the quality, nature and solids content of the raw materials used in the process do vary considerably.
In addition, there was also the problem of the rotors and seals being damaged by the aggressive nature of the pumped media and its temperature.
The three types of WCB pumps now used at the plant are the Universal II 45, Universal 15 and Universal 18.
All three pump types operate on the circumferential-piston principle, where arc shaped rotor wings (pistons) travel in annular shaped cylinders machined in the pump body.
The resulting long sealing path reduces slippage and produces a smooth flow of product without destructive pulses or pressure peaks, and without valves or complex parts.
For high viscosity fluids, the large fluid cavities of the rotors, together with the large easy entry anti-cavitation ports, allow efficient pumping of slurries and liquids containing solids of the nature encountered in biodiesel processing.
Providing flow rates of 1000-1500L/h the WCB U45 pumps are employed on the GLP acidulation and neutralisation lines where the abrasive nature of the fluid presents a problem.
Acidulation is the process used for separation and this involves the addition of a concentration of sulphuric acid into the mix to bring down the pH level.
From there the fluid is transferred to a centrifuge and into a neutralisation tank where an alkaline based substance, which also has its own handling issues, is added to bring the pH level back to neutral.
The WCB U15 and U18 pumps are used on the BFO lines immediately after distillation.
Argent Energy uses two distillation columns to produce BFO.
The two distillation columns clean or separate the heavier phase of the fuel oils to give a lighter phase.
The first column splits the heavy phase oil and the second column provides a further split to produce the desired lighter phase BFO.
Giving flow rates of 800kph and 400kph respectively, the U18 is used after the first column and the U15 after the second column.
Both these pumps have proved to be capable of withstanding both the temperature of heavier phase fuel oil, which can reach 120C, and its make-up.
In addition, the high temperatures involved can lead to material crystallisation has not had any impact on pump performance.
Argent Energy reports that the attraction of the WCB Universal pumps is the ability of the O-ring seals to withstand the temperatures required for the process, and the rotors to resist attack.
The original pumps were constantly running at 100%, whereas the replacement WCB pumps only operate at between 30 and 40%.
The benefits of this are higher operating efficiency levels and longer working life.
After 18 months operation, the pumps are reported to be achieving the levels of service required and have been trouble-free.
With the old pumps, the engineers always had to remove the pump faces and clean out the rotors.
With the WCB Universal pumps, maintenance has been restricted merely to O-ring and seal inspection due to fair wear and tear.
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