废水设计：排泥设备简介及污泥的深度处理(英文)讲解.ppt

Processing and Treatment of Sludge;目录;Part A;Generalized sludge processing flow diagram;Part B;SLUDGE AND SCUM PUMPING;Other types of pumps such as hydraulic piston slurry pumps have also been used to pump sludge. Chopper pumps are used extensively for pumping scum containing rags, plastics,and other fibrous materials that require shredding. The advantages and disadvantages of each type of pump are summarized in Table 13–14.;Plunger Pumps;The advantages of plunger pumps are as follows:;6. Discharge pressure limitations are approximately 10 to 11 bar (150 to 165 lbf/in.2). (1bar=100kPa） 7. Heavy sludge concentrations may be pumped if the equipment is designed for the load conditions.;Plunger pumps come with one, two, or three plungers (called simplex, duplex, or triplex units) with capacities of 2.5 to 3.8 L/s (40 to 60 gal/min) per plunger, and largermodels are available. Pump speeds should be between 40 and 50 strokes per min.Because grease accumulations in sludge lines cause a progressive increase in head with use, heavier duty pumps should be designed for a minimum head of 6.9 bar (100 lbf/in.2).Capacity is decreased in constant speed pumps by shortening the stroke of the plunger; however, the pumps seem to operate more satisfactorily at or near full stroke. For this reason, many pumps are provided with variable-speed drives for speed control of capacity. A plunger pump differs from a centrifugal or recessed impeller pump in that its discharge is pulsing due to the action of a piston; consequently, the actual flow while sludge is moving in the pipeline is greater than average pumping capacity. The headloss calculations, therefore, must be based on the peak pulsating flow rather than the design flow. The factors given in Table 13–15 can be used to account for the actual peak pulsating or instantaneous flow.;Progressive Cavity Pumps;For example, if a 9.5 L/s (150 gal/min) pump is required the pump selection should be sized for an additional 50 percent or a pump