Fig 1: Efficient and low-maintenance systems, like the EcoTrans MULTISAFE® pump from FELUWA, are required in process engineering industry in order to fulfil the plant operators’ current and future demands. Picture: FELUWA
The EcoTrans MULTISAFE® pump from FELUWA is a hermetically sealed, hydraulically activated, compact, economical MULTISAFE® double hose-diaphragm pump with in-built compressor and bypass flow control for pressure ranges up to 16 bar. A pump technology that till now was only available for the continuous operation with expensive process pumps (> 8000 h MTBR and high energy efficiency).
Conveyance of aggressive and abrasive media in the low pressure range
Up to now, only a limited selection of energy and wear-intensive pump technologies was available for the conveyance of abrasive slurries in process engineering industry or for aggressive fluids in chemical industry for low pressure ranges below 16 bar. The EcoTrans MULTISAFE pump design is regarded as real alternative to traditional air-operated diaphragm pumps and rotating displacement pumping systems.
The demand of the process engineering industry for an energy-efficient, low-maintenance technology saving operating costs was answered through the development of the EcoTrans MULTISAFE®. It provides an economical pump technology for low pressure ranges which till now was only available for large process pumps.
Fig 2: The in-built piston compressor provides optimum filling of the pressure air vessel and thus ensures negligibly low pulsation.
The EcoTrans MULTISAFE® product range (see Fig. 1) represents the latest generation of hydraulically-activated double hose-diaphragm pumps. This type of pump is particularly utilized for critical applications, mechanically abrasive and chemically aggressive liquids as well as highly viscous media (even with particles) of different consistencies. Depending on the respective medium, the dry-matter content can be up to 80 %.
The pumps operate as a stand-alone system. The in-built piston compressor for feeding of the pulsation dampener omits the need for any external media supply in the form of compressed air, water, etc., except the power supply for the electric drive (Fig. 2).
The high energetic and volumetric efficiency as well as the long service life of the hose-diaphragms reduce the operating and maintenance costs to a minimum. The hose-diaphragms, which are usually not considered a wear part when compared to conventional flat diaphragms, are designed for a service life of more than 20,000 operating hours. If utilized correctly, the costs for spare parts only amount to 2 % of the acquisition costs (CAPEX) per year.
In several field tests under real production conditions the pumps have already demonstrated their reliability for the handling of abrasive fluids.
Functionality and mode of action
The EcoTrans MULTISAFE® pump's mode of action is essentially based on an oscillating piston, which periodically increases or decreases the respective inner pump or working space of the outward hermetically sealed hose-diaphragm by means of hydraulic fluid (oil or water hydraulics). The suction and discharge lines are thereby alternately connected to the inlet and outlet valves. The displacement mechanism performs a simultaneous suction and discharge stroke per operating side with each stroke. During the suction stroke, a respective amount of liquid will pass through the suction pipe into the pump working chamber through the opened suction valve. During the discharge stroke, the conveyed liquid is displaced into the discharge pipe through the now open valve, while the suction valve seals the suction side.
The EcoTrans pump is safe against dry running condition, equipped with a pressure relief valve in the hydraulic system and Industry 4.0 compatible. The cylindrical shape of the diaphragm facilitates the favorable flow behavior, guarantees material-friendly conveyance and is also perfectly suitable for pumping of heterogeneous fluids with solid particles, without any actual wear.
For the handling of chemically aggressive fluids a broad range of hose-diaphragm materials is available. They thus guarantee the process-secure chemical resistance for almost all conveyed media.
Taking advantage of the gravity effect
Customized pump systems are available depending on the influence of the particle density, sedimentation or buoyancy speed: traditional pumping from the bottom to the top for fluids with buoyancy speed and DFT (DownFlow Technology) for media which tend to settle and cause blockages.
With DFT, the traditional pumping principle is literally turned upside down, which means flow from the top to the bottom of the pump using the effect of gravity. Thus, sedimentation within the pump is reliably avoided. The consistent modular system allows for individual on-site adaption.
Additional solutions which ensure SIP and CIP cleaning processes to enable “puddle-free” draining are available.
In-built piston compressor
Open pulsation dampeners (so-called air vessels) are utilized to reduce the pressure and flow fluctuations resulting from the oscillating operating behavior and to equalize the subsequently developing pressure spikes.
The in-built compressor is used to solve the problems which are associated with the gas filling of the air vessel being drained with each stroke due to the gas-solubility of the conveyed material. The described double hose-diaphragm pump in modular version was designed in such a manner that the piston rod, which is guided on two sides, can optionally also be used as in-built compressor. The in-built piston compressor reliably ensures that during each return stroke of the piston rod a small amount of filtered air (or gas) is sucked through a valve into the compressor chamber. During the forward stroke of the piston rod, this amount of air is fed into the air vessel via a non-return valve. Through this, the existing volume of air in the air vessel is always perfectly supplemented, and the residual pulsation is reduced to a minimum (see Fig 3.).
The attained dampening does not only facilitate a significantly smoother conveyance, but also a greater degree of efficiency, because the pressure fluctuations are very low. The in-built compressor also enables the utilization of low-cost single-acting pumps with low "peak to peak" pressure pulsation, where till now only expensive double or triple-acting pumps could be used.
Fig. 3: Pressure gradient with 15 bar (simplex pump, flow rate 2.5 m³/h, air vessel capacity 10 liters).
Internal flow rate regulation
The EcoTrans MULTISAFE® employs the same flow rate regulator as the high pressure pumps. It utilizes hydrodynamic principles to reliably regulate the position of the double hose-diaphragm as well as the highly efficient internal flow rate reduction in case of filter press feeding and similar applications, without the need for a costly and ineffective bypass regulation.
The expansion of the existing range of pumps created with the EcoTrans MULTISAFE® meets the current and anticipated future demands of plant operators, who are continuously striving to create a competitive advantage. With the constant pressure to implement efficient, low-maintenance as well as effective systems, this pump type will offer an opportunity to reliably fulfill these requirements.