PuK - Process Technology & Components 2022

Pumps and Systems

Pumps and Systems Diaphragm metering pumps Reduce manufacturing costs by 40 %: Pump design using the example of the ecosmart LCC and LCD units Product development using state-of-the-art project management, design and simulation methods Thomas Bökenbrink Many areas of the chemical and oil and gas industries require pumps that operate reliably and deliver high output, but have low investment costs at the same time. The proven hydraulic actuated ecosmart diaphragm metering pump from LEWA GmbH, for example, was designed specifically for these requirements. Suitable for operating pressures up to 80 bar and flow rates up to 300 l/h, it has already been in use for several years in many industries and a wide variety of applications. In order to cover higher flow rates in the future, it is currently being supplemented with two more powerful variants, the LCC and LCD. For their development, the R&D department worked out a design concept based on an indepth evaluation of the LCA model, the use of proven diaphragm technology and the requirement of low investment costs. The latter could be achieved by using series parts from the existing modular system that is already cost-optimized, as well as by simplifying components and reducing the number of parts per pump. In addition to traditional simulation methods, such as strength analyses according to the FEM method and computational strength analyses according to the FKM guideline, for the first time, the company also used the smoothed particle hydrodynamics method (SPH for short). This method is used in the automotive industry, for example, to simulate fluid movements. The result of the development work was a new modular system consisting of three drive unit performance classes and the associated diaphragm pump heads. This development holds its own against the higher-priced hydraulic diaphragm metering pumps of the ecoflow series in terms of reliability, robustness and user-friendliness. Nonetheless, a 40 percent reduction in manufacturing costs was achieved in comparison. Fig. 1: In order to cover higher flow rates in the future, the LCA is currently being supplemented with two more powerful variants, the LCC and LCD. (all photos: LEWA GmbH) Fig. 2: The proven diaphragm technology with spring-supported suction stroke was used, which ensures high operational reliability and fatigue strength for the diaphragm as a core component. While numerous processes in a wide variety of industries, such as the chemical industry, require reliable units, relatively low discharge pressures in the low double digits also allow for less complex, more cost-effective pump technology at the same time. Therefore, pump manufacturers usually also have units in their portfolio that cover these reduced requirements. For example, in addition to the proven, highly flexible, hydraulic diaphragm metering pump series, the Leonberg-based company has also been offering a less expensive diaphragm metering pump for several years. With the LCA model, however, a flow rate of up to 300 l/h was previously only possible in the singlepump version at operating pressures up to a maximum of 80 bar. In order to be able to cover higher flow rates with this series, the pump manufac- 42 PROCESS TECHNOLOGY & COMPONENTS 2022

Pumps and Systems Diaphragm metering pumps turer's engineers developed two additional, larger pump variants starting in 2019. The aim was to scale up the diaphragm metering pump to a higher capacity at the same proven safety level and using high quality own components, but without significantly increasing the low investment cost typical for this pump series. This was to be achieved by a consistent modular principle within the pump series, as well as a strict focus on the essential functions and features. Reducing costs while maintaining operational reliability and fatigue strength Fig. 3: The central, completely redesigned diaphragm drive, in which all hydraulic functions are now integrated, also plays key role in the technical design. For the development project, the engineers worked out a design concept based on the analysis and evaluation of the predecessor product, the LCA. It involves the use of proven diaphragm technology with spring-supported suction stroke, which enables the very high operational safety and service life of the diaphragm as a core component and thus contributes significantly to the great robustness and reliability of the diaphragm metering pumps. In addition, components and assemblies were to be largely simplified in order to achieve the targeted cost reduction compared to the ecoflow series. Among other things, the sealing concept of the pistons was changed from piston rings to a gap seal and the manufacturing process of the diaphragm bodies was adapted. In the future, manufacturing will change from the use of solid 316L material to investment casting, which enables the manufacturing costs of this component to be reduced by more than 50 percent. There is also an integrated pressure relief valve, which is made up of significantly fewer individual components. “Since fewer components produce fewer costs – including from a logistics and process perspective – reducing the number of parts is also an essential part of the design concept for the new pumps,” explains the Team Leader Research & Development Mechanics of the pump company. For example, the same oil was used for gear and hydraulic functions and the plunger was directly connected to the connecting rod of Fig. 4: In the future, the diaphragm bodies will no longer be made of 316L solid material but will be manufactured using the investment casting process, which has reduced the manufacturing costs of this component by more than 50 percent. the crank drive. The elimination of a plunger rod, typical of these pumps, was made possible by a clever rearrangement of the power-transmitting components. The central, completely redesigned diaphragm drive, in which all hydraulic functions are now inte- grated, also plays key role in the technical design. Existing series parts from existing modular systems were also used which, in terms of price/performance ratio, were clearly superior to a new design in small series production. This is where the effects of increased unit volumes have a positive impact. This applies to various components, such as worm gears, bearings, stroke adjustment and connecting rods, as well as product valves and customer connection adapters. At the same Fig. 5: There is also an integrated pressure relief valve, which consists of significantly fewer individual components (pictured: pressure relief valve from ecoflow above, from ecosmart below). time, the decision was made to transfer special customer requirements – for example with regard to the use of special materials such as Hastelloy or specialized designs for the pharmaceutical and food industries – to the more flexible ecoflow modular system in principle. PROCESS TECHNOLOGY & COMPONENTS 2022 43