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Compressed Air Systems
Published in Stephen A. Roosa, Steve Doty, Wayne C. Turner, Energy Management Handbook, 2020
Pneumatic diaphragm pumps are positive-displacement pumps that use compressed air to drive the pumping process. Such pumps are used frequently in chemical processing or transporting of abrasive liquids containing solid particles, for which standard centrifugal pumps are not suitable. As an energy-saving measure, pneumatic diaphragm pumps can be replaced with electric diaphragm pumps or centrifugal slurry pumps, depending on the application. However, pneumatic pumps are appropriately suited for some applications, particularly ones involving volatile environments or flammable materials where electric currents could prove hazardous.
Process Design Considerations for Large–Scale Chromatography of Biomolecules
Published in Kenneth E. Avis, Vincent L. Wu, Biotechnology and Biopharmaceutical Manufacturing, Processing, and Preservation, 2020
Richard Wisniewski, Egisto Boschetti, Alois Jungbauer
Positive displacement pumps with rapid suction and slow discharge, although used in liquid chromatography laboratory instruments, have not yet found a place in industrial systems. Check valves in diaphragm pumps not only require periodic maintenance, but they also may cause problems such as worn seats or broken springs (in the spring-loaded valves). An additional negative aspect is the possibility of check valve wear material entering the process stream. Users should inspect the available check valve designs offered by a pump manufacturer and select the valves with the best sanitary features.
Hydraulic Machines
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
A diaphragm pump is composed of a chamber used to pump the fluid: a diaphragm that is operated by either electric or mechanical means, and two valve assemblies—a suction and a discharge valve assembly (see Figure 7.17). A diaphragm pump is a variation of the piston pump in which the plunger is isolated from the liquid being pumped by a rubber or synthetic diaphragm. As the diaphragm is moved back-and-forth by the plunger, the liquid is pulled into and pushed out of the pump. This arrangement provides better protection against leakage of the liquid being pumped and allows the use of lubricants that otherwise would not be permitted. Care must be taken to assure that diaphragms are replaced before they rupture. Diaphragm pumps are appropriate for discharge pressures up to about 125 psi, but do not work well if they must lift liquids more than about four feet. Diaphragm pumps are frequently used for chemical feed pumps. By adjusting the frequency of the plunger motion and the length of the stroke, extremely accurate flow rates can be metered. The pump may be driven hydraulically by an electric motor or by an electronic driver in which the plunger is operated by a solenoid. Electronically driven metering pumps are extremely reliable (few moving parts) and inexpensive.
Exergy assessment of an Organic Rankine Cycle for waste heat recovery from a refrigeration system: a review
Published in Chemical Engineering Communications, 2023
Prateek Malwe, Bajirao Gawali, Juned Shaikh, Mayur Deshpande, Rustam Dhalait, Shivani Kulkarni, Vaishnavi Shindagi, Hitesh Panchal, Kishor Kumar Sadasivuni
In ORC, the diaphragm pump is the most popular. Zeleny et al. (2017) conducted experiments and showed that for low-power ORC, a commercial gear pump (with minor modifications) delivers higher isentropic and overall electrical efficiency. The significant losses in the pump-motor-VFD system are electrical rather than mechanical. The article by Dutta and Borah (2018) recommends utilizing a gear pump instead of a standard diaphragm pump in low-power ORCs. For giant and modest ORCs, Zhao et al. (2019) preferred turbines and scroll type expanders, respectively. For experimental and theoretical research, Jradi et al. (2014) used an ORC-based solar biomass-driven micro collective power and heat generation (micro-CHP) system to give inhabitants electrical and thermal needs while protecting the environment and increasing economic progress. The isentropic efficiency of the expander has been enhanced by 80 %. Low isentropic efficiency, and high heat losses are difficulties with the microscale ORC. The CHP system’s overall efficiency is 83 %. The CHP system outputs a maximum of 500 W of electric power and 9.6 kW of necessary heat across the condenser when the organic Rankine cycle (ORC) efficiency is 5.7 %. Eicke and Smolen (2015) intend to build a small-scale ORC system with a reliable expansion device. The findings indicate that a 1 kW ORC with scroll expander can aid process improvement and emotional impacts. The article also mentions solar collectors in conjunction with the ORC system to keep the system running.
Tribological Investigations of Silicon Nitride Lubricated by Ionic Liquid Aqueous Solutions
Published in Tribology Transactions, 2019
Johannes Kurz, Tobias Amann, Andreas Kailer
Tribological test methods outside of engines for the piston ring–cylinder liner system were developed in Woydt and Kelling (40). The authors provide parameter settings for an application-oriented load spectrum to simulate the tribological behavior in the upper part of the cylinder liner of a piston ring–cylinder liner. The settings used in this article refer to the work of Woydt and Kelling (40) (Table 2). The surface contact used in this article permits an application-oriented contact pressure of approximately 2 MPa, which corresponds to the references in the literature (Richard, et al. (41); Küntscher and Hoffmann (42)). The maximum slide way pressure between the piston skirt and cylinder liner is approximately equal to the contact pressure between the piston ring and cylinder liner at a combustion pressure of approximately 1.5 to 6 MPa. In order to achieve a defined plane-parallel contact and to identify suitable running-in conditions for the tribological system, the contact surfaces were rubbed at 5 MPa and 0.08 m/s sliding speed without lubrication. The friction tests were then carried out at 30 and 100 °C contact surface temperatures. Permanent lubrication was provided by a reciprocating diaphragm pump.
Comparison of commercial baker’s yeast versus bacteria-based membrane bioreactors for landfill leachate treatment
Published in Environmental Technology, 2018
M. C. S. Amaral, G. C. B. Brito, B. G. Reis, L. C. Lange, W. G. Moravia
Submerged hollow fiber microfiltration membrane modules were used in both MBR (poly(etherimide), cut-off = 0.45 μm, packing density of 500 m² m−3, and filtration area of 14 and 0.04 m2 for the MBRb (MBR inoculated with bacterial sludge) and MBRy (MBR inoculated with baker’s yeast sludge), respectively). The membranes were supplied by PAM Membranas Seletivas Ltda. The MBRb had three tanks: a feed tank that operated with an effective volume of 10,000 L, a 3000 L biological and membrane tank, and a 200 L storage tank for permeate. The MBRy had three tanks: a feed tank that operated with an effective volume of 30 L, a 10 L biological and membrane tank, and a 20 L storage tank for permeate. For both MBRs, a diaphragm pump was used to promote both the MF and backwash. For the MBRy, a peristaltic pump was used to dose sulfuric acid to maintain the pH of biological sludge in 3.5. Further information about the design and schematic diagram of the MBR are detailed in Andrade et al. [14] and Amaral et al. [15] (Figure 1).