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River intakes
Published in Arved J. Raudkivi, Sedimentation, 2020
For intakes on a bend, the simplest is an opening or slot in the outer bank. For small diversions the entire intake structure could be prefabricated (Figure 3.15). The slot, with debris screen, is placed just below the river level at low flow, but as high as possible above the bed. Even an entrance slot panel can be used that moves up and down with a river level as it rises and falls. Such a panel allows one to divert water always just below the surface and reduces the sediment diversion essentially to that of wash load. With increasing diversion flow rate, the sophistication of the structures increases but not the concept. Frequently, a settling basin is installed at the intake to remove suspended sediment before the water is conveyed to a treatment plant. These basins have to be equipped with suitable flushing system for cleaning.
Preliminaiy Treatment
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
Settling basins can be either circular or rectangular or are designed to operate on a continuous flow-through basis. Circular settling basins frequently are called clarifiers. Sedimentation basins can be divided into the four zones: inlet, clarification, sludge, and outlet as shown in Figure 14. The suspension to be clarified is admitted to the basin through the inlet zone. Separation of the solids from the liquid takes place in the relatively quiescent clarification zone. The clarified liquid or effluent is then removed through the outlet zone. Separated solids are allowed to accumulate, compact, and are then withdrawn from the sludge zone. Figure 14 shows the flocculation process in settling basins.
Introduction
Published in Shaimaa Abd Al Amear Theol, The use of Delft3D to simulate the deposition of cohesive and non-cohesive sediments in irrigation systems, 2020
Settling basins are used in order to trap sediments and to make them deposited in certain locations where they can later be removed as a maintenance practice (Lawrence et al., 2001). A considerable amount of money is invested in order to remove the silting, however, in some schemes, sediment settles faster than they can be removed (Lawrence, 1998). The low settling velocities for sediments cause a long adaptation length before sediment concentration profiles adjust to a new set of hydraulic conditions after the disturbance and mixing introduced by a hydraulic structure as a gate (Lawrence, 1998).
Surface-dwelling soil macrofauna and ground beetles (coleoptera: carabidae) of metal post-mining spoil heaps–community composition and potential risk element bioaccumulation
Published in Chemistry and Ecology, 2021
Beáta Baranová, Lenka Demková, Július Arvay
The material of surface-dwelling soil macrofauna and ground beetles was sampled within two metal post-mining areas in Eastern Slovakia, Krompachy and Zlatá Baňa(Figure 1). Krompachy post-mining area (GPS: 48° 54’ 52.773792″ N; 20° 52′ 22.7764893″ E), localised in the middle Spiš region, has been well known by the intensive gold, copper and silver mining and smelting activities since the thirteenth century. In the eighteenth century, iron was mined there. Nowadays, mining-related activities are significantly limited. The waste from mining and smelting activities in approx. 26.5 mil. tons is deposed at spoil heaps and coal-ash settling basin [4]. Zlatá Baňa post-mining area (GPS: 48° 56′ 39.9591562″ N; 21° 26′ 17.1697998″ E) is well known by the gold, antimony, coloured metal mining which started during the sixteenth century and ended in the 1990s. Study area is localised in the Slanské vrchy Mts., with dominance of mixed, beech, oak and hornbeam forests [7].
Hydro-abrasive erosion in hydro turbines: a review
Published in International Journal of Green Energy, 2018
Saurabh Sangal, M. K. Singhal, R. P. Saini
Pandit et al. (2007, 2008) discussed the alternative devices for sediment handling; hydro-cyclones with different geometries (Castilho and Medronho 2000) and settling basins of Jhirmuk hydropower plant, Nepal (3 × 4.2 MW, Francis turbine, H = 201.5 m). They presented the comparison of sediment removal efficiency, the removal efficiency of larger hydro-cyclone found as close to smaller hydro-cyclone (95% vs 96.8%). In contrast, a very low efficiency of gravity settling basin was noticed as compared to hydro-cyclone. By the addition of two large settling basins the trapping efficiency has increased to just 32.5% from 17% as shown in Figure 10. The flushing discharge as 3.6% is to be enough to achieve efficiency as high as 96%. Based on the performance, hydro-cyclones may be used as an alternative and effective device to exclude suspended sediment from water coming into power house, especially for high- and medium-head hydropower plants located in Himalayan river basins. In the addition, the performance of the vertically oriented hydro-cyclone has added advantage over conventional settling basins in minimizing the space requirement in steep and rugged topography of Himalayan catchment.
Industrial application of parallel integrated cyclone separator equipment in the ethylene decoking system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Liang Ma, Lv Peng, Wenjie Lv, Wei Yuan, Qisong Shen, Zhihuang Zhao, Peng Liang
First, the ethylene pyrolysis furnace (3) is stopped. Second, the high-pressure fan (1) is used to provide high-pressure air to the furnace as a medium for burning, and fuel gas as the air source for coke burning is provided simultaneously. The oxygen gas reacts with the coked scale inside the furnace under a high temperature to oxidize the coked scale and loosen it on the surface. The coke particles that fall off go to the next unit along with the air flow composed of high-temperature dust-laden gas. After passing through the quench exchanger (4), quench cooler (5), and heat exchanger (6), the high-temperature gas is cooled from the initial temperature of 850°C to 400°C. The ambient-temperature water supplied by the water pump (2) generates low-pressure steam and hot water for use in the factory after passing through the quench exchanger (4), quencher cooler (5), and heat exchanger (6). After cooling, the gas carries the particulate pollutants to the parallel integrated cyclone separator (7) for gas–solid separation. The solid particles are separated from the gas and flow to the settling basin (8). At the same time, rinse water needs to be infused continuously to the middle and lower parts of the parallel integrated cyclone separator (7) to rinse the coke particles that are separated. The supernatant liquid of the settling basin is pumped by the water pump for recycling. The purified gas flows to the chimney (9) and is absorbed by the atmosphere. Sampling sites that controlled with a sampling valve (10) are set in the gas inlet and outlet of the cyclone separator (7) to test the dust content of the gas.