FELUWA developed system for automatical adaption of gas volume for optimum dampening

A constant flow rate is essential for many mining or process engineering applications and varying operational parameters are a challenging task for operators. Whenever oscillating displacement pumps are utilised for challenging applications, various designs are used to compensate the occurring design inherent volume flow fluctuations. To ensure constant operating conditions, individually adapted traditional pulsation dampeners with air or gas cushions (pressure air vessels) or hose-diaphragm pulsation dampeners (PULSORBER) with nitrogen-filled accumulators are used. Fluctuating and flexible operating parameters require a further development of proven systems.

PULSATROL 900

FELUWA has developed a system which automatically adapts the gas volume in the PULSORBER to attain an optimum dampening solution at fluctuating operating conditions.

Automated filling pressure variation:

The increase of the operating pressure results in a reduction of the balancing gas volume in the pulsation dampener and hence in reduced pulsation dampening. If operating pressure decreases the balancing gas volume prevents effective pulsation. Consequently, the gas volume causes a vertical movement of the guide rod, whose position is recorded by sensors.

Depending on the position of the guide rod, nitrogen is added under excess pressure from an external source to the gas tank or released into the atmosphere. This ensures that the gas cushion in the pulsation dampener is optimally formed throughout the entire process and the effective dampening of the pulsation allows for even, continuous flow. All required values are shown on the touch panel.

  
Undersized vs. oversized gas volume in the pulsation dampener.

During commissioning or operation the important parameters, such as the duration of the filling pulse or the minimum pressure of the nitrogen supply, can be optimised via touch screen. Filling and emptying of the PULSORBER can be regulated via touch panel in manual mode.

Moreover, the PULSATROL 900 can also be integrated into the FELUWA Pump Condition Guard Smart. The control, diagnostic and monitoring system is used for the safe and reliable operation of FELUWA MULTISAFE® double hose-diaphragm pumps.

On the basis of the PULSORBER 900 smaller pulsation dampeners with a gas volume of 45 litres are available as well and are used for smaller pumps.

Source & Graphics: FELUWA Pumps GmbH

"Reliable handling of abrasive fluids" was the topic of the first webinar with SPA member FELUWA

The first SPA webinar with member FELUWA and their presentation to a "Reliable handling of abrasive fluids" was a great success. Many participants had registered for both presentation times. The professional pump users were invited to the free webinar by this teaser in the days before.

A warning against disturbing contents? Although it was something that webinar participants on fluid handling might not expect, a warning label regarding content was displayed beforehand by the speaker of the first Star Pump Alliance webinar. The photos that were shown would make beads of sweat appear on the forehead of every plant operator: corroded impellers and other pump components that were permanently destroyed by abrasion. In the webinar, Uwe Arce from FELUWA Pumpen GmbH explained how to avoid such terrible incidents from happening in your own company.

Arce, who is a sales manager with many years of practical experience, was not only interested in demonstrating the advantages of his own products, he also explained the basics of abrasion and how it can be avoided during operation. "We want to enable users to form their own opinion and optimize their production by gaining expertise," explains Arce. In the webinar, he described the different types of abrasion in detail. Physically and chemically, abrasive liquids can damage the pump components, either through the solids they contain or through chemical reactions of the conveyed medium with the pump components.

Direct exchange with experts

The viscosity of a fluid can also affect the degree of wear, in addition to both solid content and consistency – the thicker the medium, the lower the risk of wear. Declines in conveying speed and conveying pressure can also reduce erosion. Certain types of pumps can also handle abrasive media better than others depending upon design. Here is the expert's advice: "It is essential to discuss the intended use of the pump with the manufacturer to help users make the best choice." Arce also discussed the advantages of direct communication with manufacturers in the SPA webinar. Many webinar participants used the opportunity to ask application-specific questions and to exchange information about practical solutions for various conveying problems.

Arce speaks from experience: With MULTISAFE® double hose-diaphragm pumps, FELUWA offers units that are specially designed for conveying abrasive and aggressive media reliably and with low wear.  The linear flow through the hose diaphragm and the valves ensures that the pumped medium does not come into contact with the pump head or the hydraulic chamber. These properties make it possible for the pumps to handle even the most demanding media, for example in coal gasification, feeding autoclaves, filter presses and spray dryers, in reactor feed, and in the disposal of solids.

Knowledge and competence on all channels

Whatever the required application, the member companies of the Star Pump Alliance will find a solution. "Users should benefit even more from this expertise, especially during the current home office era," emphasizes Kai Stegemann, Managing Director of the information platform for professional pump users. "Therefore, we have been providing information about the entire spectrum of offerings from our member companies in the form of a virtual trade fair with the SPAfair since May. We see webinars as a way to impart even more in-depth knowledge and to support users with specific know-how," continues Stegemann.

The user-oriented topics of the webinars, which are created and prepared by Star Pump Alliance member companies, demonstrate the great strength of the SPA. The association of medium-sized manufacturers combines a wide spectrum of expertise and in-depth knowledge of the industry that benefits all customers. After the start of the webinar series, further sessions are already scheduled.

The next Star Pump Alliance webinars

It is planned to offer two dates for each webinar so that users in all time zones can conveniently participate. Participation in the webinars is free of charge. After the webinar, all participants will receive the presentation and other useful information on the topic, even if live participation is not possible at short notice.
The next webinar is planned for December 2020. More information will follow soon.

The Star Pump Alliance webinars: You can find the webinar overview here!

Valves in FELUWA MULTISAFE® pumps characterised by their high wear resistance

The performance of oscillating positive displacement pumps depends on the condition of the valves. Especially abrasive and highly viscous media are challenging for the material. Valves that are used in FELUWA MULTISAFE® pumps are characterised by their high wear resistance. Hence, the extension of the valve service life increases the availability of the pump and the persistence of other system components. An experimental evaluation of the influencing factors of abrasive and highly viscous media on the wear of cone valves was carried out by means of a CFD-analysis.

FELUWA MULTISAFE® Pumps

FELUWA MULTISAFE® double hose-diaphragm pumps are available for flow rates up to 1,350 m³/h and pressures up to 350 bar (Figure 1). It is a hermetically sealed, leak-proof oscillating displacement pump. The double hose-diaphragm is a further development of the conventional diaphragm piston pump with several advantages. The diaphragm separates the pump casing from the fluid and allows the medium a linear flow path without any deviation. When aggressive fluids or slurries are conveyed, the pump casing is also reliably protected against wear. Besides that, the secondary hose-diaphragm ensures that no slurry enters the hydraulic unit of the pump to protect workforce and the environment. Thanks to this unique design, the check valves are the only real wear parts of this pump and are designed to handle particles up to 10 mm in diameter. Dynamic behaviour and robustness are the main goals in valve design.

Fig. 1: FELUWA MULTISAFE® Pump

In general, valve wear is caused by particles contained in slurries and their movement on the surfaces. Guide surfaces are also affected by wear due to the relative moving of the guide-face-pair according to valve kinematics. Size distribution, hardness of the particles and the rheological properties of the carrier fluid are decisive for the abrasive behaviour of the medium. But wear is also affected by the flow velocities. The velocities need to be kept below a certain level in order to prevent excessive wear.

Three different valve types are available for the use in positive displacement pumps: ball valves, cone valves and plate valves. As part of the CFD analysis cone valves have been evaluated regarding velocity and wear. Cone valves are used for fluids with high solids content and have the advantage over ball valves that they are not limited to lower stroke rates and sizes. Besides, ball valves are selected to convey chemically aggressive fluids. Plate valves are suitable for higher stroke rates, but only to a limited extent for fluids containing solids.
 

From left to right: ball valve, cone valve, plate valve

CFD-analysis and 1D-FSI-model

By means of the CFD analysis, the flow rate can be calculated with high accuracy. As part of a study, complex kinematics simulations were also carried out.

Results of the 1D-FSI-model

Figures 3 and 4 show different lift curves of the cone valve under varying conditions. In these cases, valve lift is applied over a crankshaft angle for a discharge stroke, where 0° is the start of the stroke. The standard conditions are 90 spm, 16 bar discharge pressure, a spring stiffness of 3 N/mm and spring preload of 50 N. Any deviations from that standard condition are shown in the corresponding legend. The graphs show that the operating conditions, Figure 3, have a big impact on the valve kinematics. The stroke rates in Figure 3a illustrate that the maximum valve lift rises with increased pump speed. This is rather easy to explain, because the flow rate increases proportionally to the pump speed and the valve forces automatically increase with the flow rate. Due to the enormous computing times, a separate model was developed that can predict valve kinematics with high accuracy using CFD results. The computational effort is reduced considerably allowing extensive parameter studies.
 

  
Fig. 3a: Lift curves for different stroke rates
Fig. 3b: Lift curves for different discharge pressures
 

Fig. 4a: Lift curves for different spring rates

The opening starts more and more delayed with increased discharge pressure. Further delayed valve opening increases the initial motion sequence until hitting the stroke limiter.
In Figure 4a the influence of the spring stiffness is shown. Higher spring rates improve the dynamic behavior, the oscillating amplitude is reduced and the risk of an impact on the stroke limiter is reduced.
Thus, it is evident that valves cannot be considered separately. Prior to optimisation structural parameters such as spring preload or spring rate have to be taken into account, but also the influences of operating conditions such as operating pressure and stroke rate as well as the characteristics of the pumped medium. Hence, a complex CFD parameter study cannot be carried out.

Results of the erosion simulation

In general, the erosion simulation is the second step and is based on the standard flow simulation. The difference is that the solids need to be included as a second phase in the flow.
 

Fig. 5: Calculated overall erosion rates for different concentrations of a sand-water slurry

The mass fraction is considered as normally distributed with particle diameters between 25 and 500. The particle mass flow is converted according to the corresponding volume concentration. The volume concentration is varied between 4 and 20% and the valve inlet velocity between 0.4 and 2.5 m/s. The results of these calculations are shown in Figure 9 for the SST and the SKE turbulence models. For the three concentrations, a correlation between velocity and overall erosion rate can be given in an exponential law with an exponent between 3.5 and 4.1. In the valve a combined erosion mechanism of sliding and hitting as shown in Figure 6 can be observed.
 

Fig. 6: Velocity field and particle tracks

The highest erosion rate is in the redirection zone downstream the gap between valve cone and valve seat. An exponent in this order means an increase in speed of a factor 2; the erosion rate rises by a factor 11-17. A doubling of the concentration leads solely to an increase of the erosion rate by a factor 3-4. Therefore, the solids content should always be increased by increasing the concentration, since otherwise the wear increases significantly.

Conclusions & Outlook

This paper presents a valve design process including the consideration of valve kinematics and wear locations. The valve kinematics are introduced as a 2-step model consisting of an intensive numerical investigation of the flow and a one-dimensional fluid structure interaction approach. This method could successfully be verified by experimental data and by comparison with full fluid structure interaction simulations. Compared to a full fluid structure interaction simulation, the advance of this design process is that the numerical investigation is decoupled and therefore needs to be done only once and not for each combination of any operating conditions and design parameters. This results in a flexible model which is also beneficial for the design, while a full FSI is solely useful for the final design verification. Another advantage is that this model can be independently adjusted without the valve geometry until ideal valve performance is achieved in the 1D-FSI model. In the second step, the geometric parameters of the valve design are adjusted until the pressure losses and valve forces meet the determined input data. This is one objective of the current research progress.

The implementation of erosion in the design process enables the engineer to identify weak spots at an early stage of the design process. Velocity is a crucial factor since wear increases along with velocity to the power of 4. Further investigations on wear are another objective of the current research progress. FELUWA has set up an in-house high pressure test rig with a pressure range up to 160 bar and a flow rate up to 15 m³/h, consisting of a high pressure slurry pump, a temperature regulated mixing tank and the related measurement technology in order to verify and validate the erosion model with respect to check valves. The goal is to develop an independent model for erosion alike the 1D-FSI model.

The use of these calculation models enables FELUWA to continuously optimise the valves for the MULTISAFE® pumps and to select the best valve with the best wear resistance for the individual application.

Source & Graphics: FELUWA

FELUWAs pump of type SGL – 1 M 190 is versatile usable for various applications

With the pump type SGL – 1 M 190, FELUWA provides a versatile pump which has been successfully used in various areas of application for many years. The pump has proven to be especially suitable for spray dryer feeding with highly abrasive media.

Over the years, the electrically driven SGL – 1 M 190 piston diaphragm pump has made a name for itself as spray dryer feeding pump. The robust construction consisting of a horizontal worm gear in combination with a stainless steel pump head, integrated flow control and adjustable overpressure safety provides the operators with a solid plant basis.

Thanks to the modular design, the pumps can be realised with one or two pump heads and individually equipped with different hose-diaphragm materials, thus ensuring reliable transport of a wide variety of media. Of course, an ATEX-compliant version for potentially explosive environments is also available.

Simple and reliable operation

The pump is characterised by its simple handling. The flow rate can be adjusted to the required process parameters using a manual bypass valve or a frequency-controlled motor. Depending on the set-up, the pump achieves a flow rate of up to 1,000 liters per hour at a pressure of up to 30 bar.

Also applicable as metering pump

Due to the increased demand for metering pumps, the properties of the SGL – 1 M 190 as a metering pump were examined in more detail in terms of flow rate accuracy.
The test report has confirmed that the SGL – 1 M 190 achieves a high level of flow rate accuracy of > ± 1% by means of targeted adjustments in pump hydraulics. Metering is carried out either by means of the manually adjusted bypass valve or by frequency-controlled motor. In addition to spray dryer feeding, the pump is thus also suitable for further areas of application, such as pumping of all types of slurries or abrasive and viscous media, acids and bases.

Tried and tested in practice and proven over many years

For many years, the SGL – 1 M 190 piston diaphragm pump has proven itself as spray dryer feeding pump, even in critical applications. As a metering pump, it also reliably conveys abrasive media, is low-wear and easy to handle.

Source & Picture: FELUWA GmbH

The pump according to EHEDG guide lines ensures purity, cleanliness and hygiene for food production

Purity, cleanliness and hygiene rank first when it comes to food production. Nowadays, hygienic design is more important than ever to avoid microbiological contamination or foreign objects/particles in food. But the food market is subject to constant changes and fast-moving. Consumers prefer fresh produce which should be easy to prepare or require little or no heat treatment. In addition, the demand for products with less sugar, salt and preservatives has increased. There is an enhanced risk of a growing number of microorganisms in food enforced by these developments. This results in increasing requirements for machines in hygienic systems, such as pumps that come into direct contact with the product in food production.

FELUWA MULTISAFE® double hose-diaphragm pump in hygienic design

FELUWA MULTISAFE® pump in hygienic design

FELUWA recently delivered a pump in hygienic design to convey glucose solution in accordance with the EHEDG design guidelines. The TGK 300 – 3 DS 100 achieves an operating pressure of 105 bar and a flow rate of 60 m³/h.

Contamination of the pumped medium, in this case the glucose solution, would result in high costs. The product would be unusable and the worst-case scenario would be a loss of trust among customers and the closure of the plant. FELUWA MULTISAFE® pumps in hygienic design are suitable for the abrasion-free and gentle transport of food with maximum cleanability. Hence our pumps ensure safe operation in food production with reliably good quality and thus increase product safety.

Another advantage of the FELUWA MULTISAFE® pumps is the hygienic component design, as they are safe and clean due to the hermetically sealed separation of product and drive end. A pair of redundant hose-diaphragms, which are arranged one inside the other, guarantee double hermetic sealing from the drive end. The conveyed fluid will neither come in contact with the pump head nor with the hydraulic area. In the past, other manufacturers used plunger pumps to pump glucose. With this design, however, the plunger is in contact with the medium, glucose and lubricants mix and the fluid is contaminated.

The small number of medium-wetted parts and the ideally shaped pump head in terms of flow technology are characteristic advantages of the MULTISAFE® double hose diaphragm pumps. They guarantee optimum cleaning options and gentle transport.

Cleanability is crucial

In order to meet the requirements of hygienic design, all components and pipes in contact with the medium must be (self-) draining and easy to clean. Horizontal surfaces have to be avoided – they should always be designed to be slanting to one side, so that liquids can drain freely without leaving residual fluid.

In addition, the selection of fluid-contacted materials is important to ensure optimum cleanability and thus the highest level of cleanliness and biological safety. The wetted parts of the pump conveying glucose solution are made of 1.4404 with an electropolished surface. Furthermore, NBR hose-diaphragms with FDA certification are used.

The use of DownFlow valves with floating balls allows for optimum cleaning / CiP flushing without dismantling the components or manual cleaning. Additional setup and work steps are redundant, the pump can easily run completely dry by opening the flushing connection. In the process the ball drops and opens the gap between the ball and the valve seat, so that the medium behind it can also drain off. Diaphragm pumps with conventional check valves require special lifting devices to lift the valve body for emptying the pump – these can be omitted in FELUWA’s design. The hygienically designed pumps of the MULTISAFE® series also allow sterilisation with superheated steam.

EHEDG-conformity

In all areas of food and beverage, MULTISAFE® double hose-diaphragm process pumps ensure safe food production in accordance with EHEDG guidelines.

Pump head in hygienic design

Source & Pictures: FELUWA Pumpen GmbH

Safe and resource-saving pipeline transport of fluids up to 300 km with just one pump station

By means of hydrotransportation, solids in a carrier fluid, which is mainly water, can be transported through a pipeline over distances of up to 300 km. FELUWA MULTISAFE® double- hose diaphragm pumps enable the efficient and reliable pipeline transport of solid-liquid mixtures with only one pump station. These hermetically sealed positive displacement pumps not only achieve a significantly higher level of cost-effectiveness than traditional transports by road or railroad, the process is also environmentally friendlier and conserves natural resources.

FELUWA MULTISAFE® double hose-diaphragm pumps are unique piston diaphragm pumps which have been used in hydrotransport for decades. The double hose-diaphragm ensures separation of the wetted parts from the drive end and guarantees reliable and low-wear transport of abrasive, aggressive and challenging media. Furthermore, piston diaphragm pumps offer a cost-efficient, reliable and particularly low-emission alternative whenever traditional means of transport fail in locations that are difficult to access.

Field-tested FELUWA MULTISAFE® double hose-diaphragm pumps

FELUWA Pumpen GmbH delivered three MULTISAFE® pumps type TGK 500 - 3 DS 350 to a copper producer in Russia. They will be used in a mine for the disposal of thickened tailings. Important ecological aspect: By pumping thickened mine waste, considerable amounts of water and energy can be saved.

In the case of the Russian copper mine the goal was to extend the operating life of the existing reservoir. This resulted in the necessity to reduce the water content in the tailings. The increase in the solids content from 17 to 70 percent leads to a heightened discharge pressure of 80 bar, which is still in the lower range for FELUWA pumps, since they are able to handle pressures up to 350 bar.

Another advantage of this approach is that the thickened mine waste could be pumped into the old open-cast mine and be recultivated afterwards. Building a new reservoir became redundant.

In summary, the high solids content in the medium saves up to 44 million m³ of water per year. Useful for comparison: The football stadium “Allianz Arena” in Munich, Germany, corresponds to a volume of approx. 3 million m³ and could be filled with this amount of water more than 14 times a year. The FELUWA MULTISAFE® double hose-diaphragm pumps thus contribute to considerable savings in natural resources at maximum process reliability.

Quintuplex design of MULTISAFE® double hose-diaphragm pumps

The pumps the success story of success of the FELUWA MULTISAFE® pumps. Among other things, FELUWA is proud to have delivered the world's largest piston diaphragm pumps. Three 5-head Quintuplex double hose-diaphragm pumps have been successfully utilised for years in a copper mine in Mexico to reliably transport an extremely aggressive mixture of seawater and solids.

Source & Pictures: FELUWA Pumpen GmbH

FELUWA offers cost-efficient and process-safe pumps for corrosive and toxic media

The selection of suitable pumping technology, as well as the energy-efficient use of raw materials, is especially challenging if the manufacturing plant operator handles corrosive or toxic media. When designing a pump specifically for the production of polyaluminium chloride, special materials were used to avoid any pump corrosion by the aggressive medium. Furthermore, the double hose-diaphragm pump meets the optimum technical requirements for this challenging process and ensures low-pulsation operation, while simultaneously providing favorable procurement and operating costs.

At the end of the process chain in many industrial manufacturing processes, a by-product is created in addition to the desired commodity. This by-product often has a commercial use. An example of this comes from an Indian production unit for caustic soda. When producing caustic soda from sodium chloride, large amounts of chloride slurry are created, an acidic and therefore particularly aggressive medium. Over the course of the process, the chloride is made to react with aluminium hydroxide in order to produce polyaluminium chloride (PAC), which is an extremely corrosive solution with a pH value of between 1 and 3. A suitable high pressure pump feeds the PAC at high temperature and a pressure of 70 to 100 bar into a spray dryer, where PAC powder in micro-fine parts is produced as an intermediate product for further use. PAC is used in water treatment and also in the cosmetic industry for making antiperspirants (deodorants).

The PAC production process presents several challenges which must be considered when selecting the suitable pump. The criteria include:

-    pressure and corrosion-resistant materials
-    hermetically sealed process
-    pressure of 70 to 100 bar
-    temperature up to 120 °C
-    low pulsation
-    optimum efficiency
-    minimum costs (capex and opex)

Titanium as material

The high pressure has to be maintained in order to achieve even granulation of the PAC powder. With pressures of up to 100 bar, metals are primarily considered as the material for piping and valves. Both Hastelloy C and titanium resist corrosion. Based on specific experiences and tests, the operator decided to have medium-wetted and pressurized parts made of titanium, whereas PTFE (polytetrafluoroethylene) was to be used for seals and to separate the wet end from the drive end.

Due to their special design, displacement pumps have proven themselves for such demanding processes at high temperatures. Screw spindle pumps and eccentric screw pumps do have low-pulsation properties, however the special requirements, such as hermetic seals and material resistances, are difficult to align with reasonable overall costs. Centrifugal pumps are not applicable because of the high operating pressure.

Undesirable pulsations

Taking the process-related requirements into account, only a plunger or piston pump can be used. In this case, the decision was made in favor of a double hose-diaphragm pump. Spray dryers are generally very sensitive to pulsations, but a triple acting pump with offset arrangement of the crank shaft/connecting rod assembly by 120° has proven successful in ensuring operation at low pulsation. Through use of an appropriately sized pulsation dampener, the residual pulsation can be reduced to less than 1.5%. Furthermore, the use of a triplex pump ensures that low pulsation is even maintained at the very low maximum flow rate of 2m³/h required for this specific spray dryer.


Fig. 1: Schematic diagram of a triplex pump with integrated pulsation dampener

Reduce slurry-wetted parts

The slurry-wetted parts of the feed line and connecting pipe, as well as the check valves and valve seats, are made of titanium. While the inner parts of traditional diaphragm piston pumps, e.g. diaphragm casing and pump cover, are in direct contact with the pumped fluid, the slurry chamber of the chosen double hose-diaphragm pump is sealed from the environment by double seals. Fabricating the pump heads from titanium was therefore not required, which contributed significantly to cost reduction.

By using a flexible double hose-diaphragm, the medium is fed through the pump in a favorable way without contact to any parts subject to pressure. The pressure within the pump casing and pump head caused by the displacement of the plungers is the same in the hydraulic fluid and in the medium, which means that the only function of the diaphragm is to separate the critical medium from the hydraulic fluid. Almost identical pressure is maintained inside and outside the diaphragm, so that the diaphragm is only subject to deformation energy and no other stress. This design helps noticeably reduce costs for maintenance and wearing parts.

Fig. 2: Traditional diaphragm piston pump (left) & double hose-diaphragm pump with hermetical sealing of the conveyed fluid and sensors (right)

Material with special properties

While the hose-diaphragm for many standard applications is typically made from NBR (nitrile rubber), this particular case of PAC application only allowed for PTFE as the diaphragm material. With this special material, which is resistant to the corrosive properties of PAC, a service life of more than two years is achieved. Valve balls and valve seats are therefore regarded as the sole real wearing parts of the chosen pump design.

Safe operation thanks to proven technology

In addition to the special features, proven serial parts offer the ideal solution regarding initial and operating costs. Additional features guarantee safe and low-wear operation. When exchanging wearing parts, in this case only the internal parts of the check valves, the pump remains integrated in the piping. Specially developed sound sensors allow condition monitoring of every individual valve. Thanks to these sensors, only the actually affected valve is subject to maintenance, which in turn reduces the operating costs.

The pump is usually driven by a variable speed motor. If two or more units are being operated in parallel, electronic crankshaft coupling is applied, which further reduces pulsation in the system, resulting in a uniform volume flow. By means of crank shaft coupling, an appropriate offsetting of the crank angle is maintained over the whole duration of the operating time, which means that two triplex pumps are working at the uniformity of a six-head pump.

Thus the used double hose-diaphragm pump combines the operator’s special requirements with the proven and tested properties of a serial product.

Fig. 3: Double hose-diaphragm pump for polyaluminium chloride production

Source & Pictures: Mr. Gänsel / FELUWA

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 solution
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.
Picture: FELUWA

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.

Special features

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).
Picture: FELUWA

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.

Conclusion:

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.