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Pumps and Turbines
Published in Henry Liu, Pipeline Engineering, 2017
A screw pump contains a rotating screw (auger) in the center of the pump cylinder (see Figure 9.7f). Fluid or fluid-solid mixture is forced by the rotating screw to move through the pump and to enter the discharge pipe. The main motion of the fluid (or mixture) inside the screw pump is in the axial direction. Thus, both screw pumps and propeller pumps are considered to be axial-flow pumps. However, while in a propeller pump the propeller is housed in a large-diameter, disklike pump cylinder, in a screw pump the screw is contained inside a small-diameter, elongated pump cylinder. The relatively small diameter of screw pumps makes it possible to rotate at speeds higher than that of other types of pumps; some have speeds exceeding 10,000 rpm. For a given screw design, the pump head or pressure increases linearly with the screw length. Design of the screw threads of a screw pump is similar to designing an auger-type extruder, though the two machines have very different purposes or functions. Applications of screw pumps include pumping fuel oil, liquid lubricant, hydraulic fluids (for hydraulic presses), and special chemicals. Similar to other pumps, they cover a wide range of pressure and discharge. Screw pumps are also called progressive-cavity pumps. This term is derived from the fact that as a screw pump turns, the cavity or space between the rotor (rotating screw) and the stator (stationary wall possessing specially designed threadlike or wavy grooves) advances forward and pushes the liquid or solid-liquid mixture forward in a positive-displacement action.
Anaerobic digestion of urban wastes: integration and benefits of a small-scale system
Published in Environmental Technology, 2022
J. R. Bautista Angeli, T. LeFloc’h, A. Lakel, B. Lacarrière, Y. Andres
In Table 5, the values describing the nature of the mix (transport cost, specific calorific coefficient, etc.) were estimated from the literature available for WW, dried FW, and GW (not ensiled). The use of a simple gravity clarifier was chosen to limit energy consumption during WW concentration. All the pumps considered were based on an SYDEX brand progressive cavity pump to accept variations in effluent viscosity. Sanitation has been counted for PS to obtain pathogen destruction. Heat recovery was also counted to valorize the heat provided during this sanitation. The reactor was admitted as composed of stainless-steel plates and the insulation made of layers of rock wool. The biogas treatment is based on H2S purification by washing with water. Finally, the liquid phase spreading was admitted for an area situated at 3 km around the district. The low quantity of compost, generated, was considered of sufficient quality for utilization by the inhabitants of the residential areas.
Diamond Nanofluids: Microstructural Analysis and Heat Transfer Study
Published in Heat Transfer Engineering, 2021
Farzin Mashali, Ethan M. Languri, Jim Davidson, David Kerns
Figure 4a shows a schematic of the experimental apparatus for measuring the heat transfer coefficient of a working fluid. It is composed of a progressive cavity pump (Moyno INC 230/460 V, 2/1 A, 3 phase motor) to circulate the liquid. A variable frequency drive (VFD) is used to adjust pumping power and can be related to the fluid flow rate. A cold plate (Aavid Thermaalloy Inc., USA) is used as the heat transfer test section (Figure 4b). The cold plate has a copper tube with an inner diameter of 7.02 millimeter as the flow path that is attached to an aluminum plate with a specific geometry to offer improved heat transfer. It has a much smaller working space than a heat sink and is capable of compacting a heat transfer length of around 3800 cm in six times smaller length. The geometry also achieves an acceptable pressure drop, which can be used in an air cooling system for the same application. Six heaters are embedded in a stand, and the stand was put under the cold plate. The stand is designed as an electronically controlled heat dissipating source. The cooling part of the system is a coil heat exchanger submerged in a 200-liters water reservoir with a temperature controller to remove the heat which had been applied through the cold plate. The whole system is well-insulated to diminish peripheral heat loss and environmental effects. Several T-Type self-adhesive thermocouples (Omega, USA) were embedded at various locations on the copper tube of cold plate. Two submerged thermocouples are located at the inlet and outlet of the cold plate to measure the fluid temperature just before and after heating through the cold plate. A flow meter (PV6008SA, Proteus Industries Inc., USA) is used to measure the flow rate.
Industrial-scale experimental study of internal-mixing air-blast nozzle for sludge atomization
Published in Drying Technology, 2023
Chulin Yu, Yulin Cui, Binfeng Liu, Yu Li, Rui Wang, Chunlong He, Jun Li, Qiang He
In this experiment, domestic sludge with a moisture content of 85.6%, a viscosity of 26 mPa·s, and a density of 786 kg/m3 was chosen from a sewage sludge treatment plant in Tianjin. Experiments required equipment and measuring instruments are shown in Figures 2 and 3. The air path consists of an air compressor, storage tank, pressure-reducing valve, ball valve, and vortex flowmeter. The flowmeter has the function of correcting the density of the working gas, and the displayed readings are the compressed air flow rate and pressure under standard conditions. The sludge path is composed of a single screw pump, motor inverter, filter, pressure gauge, and electromagnetic flowmeter. The filter is installed in the middle of the sludge side to prevent sludge clogging. Finally, the air path and the sludge path are connected to the sludge nozzle through two pipes. The air delivery capacity of the air compressor is 360 m3/h and the air delivery pressure can reach 0.8 MPa, the progressive cavity pump can deliver sludge flow up to 3 m3/h and the delivery pressure can reach 2.4 MPa. Pressure-reducing valve and ball valve are used to adjust the air pressure and flow rate, and the speed of the progressive cavity pump is adjusted by the inverter to control the sludge flow rate. During the experiment, the single screw pump is turned on first to move the sludge. Subsequently, the air compressor to avoid sludge backflow from clogging the air pipeline. Then, air and sludge converge inside the nozzle and are sprayed out under common pressure to form the spray. After the experiment, the progressive cavity pump is shut off first, followed by the air compressor. To remove any remaining sludge from the nozzle and lower the error, the air path is continually opened between every two groups of experiments.