COMPARISON BETWEEN MULTIPLE EFFECT AND VAPOR COMPRESSION DISTILLATION SYSTEMS
VAPOR COMPRESSION: SAFETY, SAVINGS AND FLEXIBILITY
In vapor compression still, the circuit of the WFI is separated from the circuit of the feed water. Moreover, the circuit of the distillate is under positive pressure. In case there should be any leakage it will be the WFI flowing out to the circuit of the feed water and never the opposite. The usual contamination problems that can arise by any multiple effect distiller after some 4-6 years of operation could therefore never happen in case of BRAM-COR Vapor Compression technology.
The special feature of the Vapor Compression Distiller, allowing to produce WFI at any temperature between 25°C and 99°C, together with the possibility to produce any quantity of WFI desired (from 0 to the maximum capacity of the plant), allows to adapt to any customer need. The same distiller can produce WFI for LVP as for antibiotics (heat sensitive injectables).
Also known as thermal vapor recompression or thermocompression system, BRAM-COR Vapor Compression still offers, thanks also to a wide range of available optional devices, not only the lowest degree of energy and water consumption of the market, but also offer the highest possible output flexibility in terms of:
• Possibility to change the hourly capacity from 0 to the highest plant capacity (this interesting option allows to drastically reduce distiller starts/stops)
• Possibility to produce distillate at any temperature from 25 up to 99°C
• Possibility to heat the equipment by steam and/or by electricity (for instance by steam, during the day and by electricity during the night, when the cost/kW is lower)
• Possibility to use feed water not only from pre-treatment plants such as the Reverse Osmosis and the Demineralizers, but also from simple and low cost softeners
ADVANTAGE OF THE BELT DRIVEN COMPRESSOR
IN VAPOR COMPRESSION STILL
We focuse on the choice of the drive type for the “turbo blower”, which mechanically compresses vapor inside the boiler. The blower is the main mechanical part in motion in a VC distiller; it can be either direct driven or belt driven. In the first case the drive shaft and the rotor coincide; in the second case the impeller shaft is belt driven by the underlying motor shaft.
Both systems have positive and negative aspects on operation and maintenance which should be carefully taken into account when choosing a distiller, but we have chosen the belt driven compressors for our STMC distillers, for many reasons, below shown.
AFFORDABLE INVESTMENT, EXTREME RELIABILITY
– The reduction of the capital cost for the equipment: a proven cost-effective technology for an affordable initial investment.
– The reliability, based on the extreme structural simplicity, ensuring an easy replacement of spare parts which can be commonly found on site.
In BRAM-COR vapor compression still, all spares can be easily replaced by non-expert mechanical staff, with reduced plant shutdowns and production stops. Even the ball bearings of the shaft can be easily replaced in short time. On one hand, STMC equipment design is conceptually advanced (minimal tolerances for impeller and heads, high performance, optimized consumption). On the other hand, each STMC is conceived for a clean, sanitary separation of the product-contact blower from the electrical motor, which is safely placed below the blower, to prevent contamination. Every piece is in sight, everything is perfectly reachable.
A few minutes are needed to open the protection carters and periodically verify the condition of the belts; common mechanical skills are required to substitute the ball bearings of the blower shaft, the risk of shutdown becomes really negligible.
Two critical factors affect direct driven compressors, due to the high number of revolution: an accelerated bearing wear and a reduced lifecycle. The replacement of rotor ball bearings, as soon as they start deteriorating, is more complex, requiring prolonged shutdowns and specialized technicians and tools.
NO CONTAMINATION, HIGHEST SAFETY
– Safety from contamination: in direct drive, the rotor is firmly anchored to a ball bearing systems lubricated by pressurized oil, which is cooled by a radiator with a pump. This compact solution has the undoubted advantage of a restrained size, but does not ensure total safety against undesired contamination from oily sediments coming from the rotor.
In BRAM-COR belt driven compressor there is no lubrication circuit. Therefore there is no oil contamination risk, if not hypothetical: the ball bearings of the impeller shaft, in fact, are lubricated with the original grease; there is no physical-mechanical stress causing grease leaks. Moreover, the process side (internal side of the compressor) is always at higher pressure than the outern side, because no pressurized oil is used for lubrication. In other words, the highest safety against oil contamination can be reached when the shaft, moving the impeller, is different from the rotor.
LONG LIFE FOR A CONSTANT WFI QUALITY
– Long lifecycle: belt driven blowers ensure a long life to the distiller and a constant WFI quality, in compliance with the international pharmacopeias, ensuring an easy validation of the equipment. Lip seals and ball bearings are due to be replaced often up to 10000 working hours. Indirect drive allows belt compressors to be “oil contamination free”, therefore suitable for pharmaceutical application.
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