pumps and puming stations.pptx

pumps for water supply and wastewater

1. Conveyance of water Pumps and Pumping Stations Thejus Engineering College

2. PUMP A pump is a device which converts mechanical energy into hydraulic energy. It lifts water from a lower to a higher level and delivers it at high pressure

3. Purpose of Pumping To lift raw water from wells. To deliver treated water to the consumer at desired pressure. To supply pressured water for fire hydrants. To boost up pressure in water mains. To fill elevated overhead water tanks. To back-wash filters. To pump chemical solutions, needed for water treatment.

4. Classification of Pumps Displacement pumps Reciprocating pumps Rotary pumps Rotodynamic pumps Centrifugal pumps Axial flow pumps Miscellaneous pumps air lift pumps hydraulic rams

5. Displacement pumps A pump in which liquid is moved out of the pump chamber by a moving surface or by the introduction of vacuum in a chamber. Reciprocating pumps Rotary pumps

6. Reciprocating pump Displacement pumps

7. Components- Reciprocating pump Cylinder - it is made of cast iron or steel alloy . Piston - the piston reciprocates inside the cylinder. Connecting rod - it connects piston and rotating crank. Suction pipe- it connects the source of water and cylinder. Delivery pipe - water sucked by pump is discharged through the delivery pipe. Suction valve - it adjusts the flow from the suction pipe into delivery pipe. Delivery valve - it admits the flow from the cylinder into the delivery pipe. Displacement pumps

8. Displacement pumps

9. Reciprocating pump Advantages High efficiency No priming needed Can deliver water at high pressure Can work in wide pressure range Constant rate of discharge at variable heads Durable and flexible Disadvantages More parts mean high initial cost (4 times than centrifugal pumps) High maintenance cost No uniform torque Low discharging capacity Pulsating flow Difficult to pump viscous fluid and fluid with sediments High wear in parts Large space requirements Displacement pumps

10. Rotary pumps The rotary motions if obtained using cames or gears with cames with gears Displacement pumps

11. components The pumping system consists of a housing an eccentrically installed rotor vanes / cames that move radically under spring force inlet valve is designed as a vacuum safety valve that is always open during operation outlet valve is oil-sealed working chamber is located inside the housing Displacement pumps

12. Working of rotary vane pump Rotor and vanes divide the working chamber into two separate spaces having variable volumes. As the rotor turns, gas flows into the enlarging suction chamber until it is sealed off by the second vane. The enclosed gas is compressed until the outlet valve opens against atmospheric pressure. The Rotor moves with the help of a motor attached to it. Displacement pumps

13. Displacement pumps

14. Displacement pumps

15. Rotary pumps No priming required Flow is free from pulsations Simple to construct Efficiency high for moderate heads and smaller discharges High initial cost Not durable-frequent replacement of cames and gears Water with sediments destroy pumps Advantages Disadvantages Displacement pumps

16. Rotodynamic pumps A  rotodynamic  pump is a pump that uses the rotation of an impeller or propeller to impart velocity to a liquid.  Centrifugal pumps Axial flow pumps

17. Centrifugal pumps Radial flow and mixed flow machines are called centrifugal pumps Open – hub to which vanes are attached Closed – plates on both sides of vane Casing of radial flow type centrifugal pump may be of Volute type Turbine type Rotodynamic pumps

18. Volute type centrifugal pump Impeller discharges into a gradually expanding spiral casing. It produces an equal velocity around the circumference and to reduce the velocity of water as it enters discharge pipe. Thus creating required pressure head. Rotodynamic pumps

19. Turbine type or diffuser type centrifugal pump Impeller is surrounded by stationary guide vanes which reduces the velocity of water before water enters the casing. The casing is generally circular and concentric with impeller. Velocity of water is more completely converted into pressure head High efficiency Rotodynamic pumps

20. Components Centrifugal pump An impeller – increase pressure of liquid Casing – acts as pressure containment vessel, helps in flowing water out of pump Shaft – transmit input power from driver to the impeller Seal – prevent leakage of pumped liquid to atmosphere Bearings – support weight of shaft assembly, carry hydraulic load, keep pump shaft aligned to shaft of the driver Coupling – connect pump shaft and driver shaft, transmit the input power from driver into pump Rotodynamic pumps

21. Rotodynamic pumps

22. Rotodynamic pumps

23. Centrifugal pump As there is no drive seal so there is no leakage in pump It can pump hazardous liquids, silts also There are very less frictional losses, high efficiency There in almost no noise Centrifugal pump have minimum wear with respect to others Compact size and small space requirements Discharge obtained is steady and non pulsating Priming is required High pressure should be avoided. Because of the magnetic resistance there is some energy losses Unexpected heavy load may cause the coupling to slip High head efficiency is low (50-80 %) Discharge varies with head of water Advantages Disadvantages Rotodynamic pumps

24. Axial flow pumps Axial flow machines are called axial flow pumps An axial flow pump has a propeller-type of impeller running in a casing. The pressure in an axial flow pump is developed by the flow of liquid over the blades of impeller. The fluid is pushed in a direction parallel to the shaft of the impeller Rotodynamic pumps

25. Axial flow pump Can be adjusted for best efficiency at varying conditions Wide range of pressure, flow & capacities Highest flow rates No excess pressure build up High cost Relatively high weight High power requirements Not suitable for suction lift Cannot handle high viscous fluids Advantages Disadvantages Rotodynamic pumps

26. Applications Positive Displacement Pumps Rotary Metering Pulsed Delivery i.e. fuel injection for engines Reciprocating Suction Lift Axial Pumps Sewage handling—Domestic, Industrial, Commercial Agriculture—Lift water for irrigation Wastewater treatment plants

27. Air lift pumps Used for pumping water from deep wells for lift of about 60 – 80m. Can be used for high lifts about 150 metres but their efficiency is generally low (25-50%) Compressed air is forced into the well through a small pipe Released through a diffuser into the eduction pipe Air water mixture in the eduction pipe is lighter and the forced upward by hydrostatic pressure

28. Air lift pump Inspite of low efficiency, an air lift pump can deliver large amounts of water from small dia wells. Not harmed by sedimented water. Cheaper, reliable and simple in operation No moving parts which may be in contact with water– used for highly acidic or alkaline water. Yield of a well, using such pump, can be increased by using more amount of compressed air. Not adopted for raising water much above the ground level, and if this is necessary, a second pump has to be installed. Efficiency is low Flow obtained is not continuous but is intermittent. Less flexible in fulfilling variable demands. In order to obtain sufficient value of submergence, the depth of submergence has to be increased and thus the well has to be made deeper than required. This increases the cost. Advantages Disadvantages

29. Hydraulic ram A kind of pumping arrangement which does not utilise any outside power and uses the principle of water hammer pressures developed when a moving mass of water is suddenly stopped. A large amount of water must be available at moderate head, so as to lift small amount of water to higher head. Can be used for lifts of order of 30m or so.

30. Hydraulic Ram

31. Hydraulic Ram Its working is simple and when once it starts functioning, practically no attention is required. The Ram is durable. It is cheap as it does not require any fuel. Considerable amount of water is wasted through a waste valve, and cannot be used at places where water is scarce. It produces considerable noise while working. ADVANTAGES DISADVANTAGES

32. Jet pumps Used for pumping water from small wells. Used for constructional works for dewatering trenches. Efficiency is low (25%) Compact and light in weight Can also handle waters containing sediments without much trouble.

33. Jet pumps

34. Selection of pump Capacity of pump Importance of water supply scheme Initial cost Maintenance cost Space requirements for location of pumps Number of units required Total lift of water required Quantity of water to be pumped

35. Pumping station

36. Pumping Station - Location The site should be away from all sources of contamination Site should be above highest flood level It should be such that the future expansion is easily possible Possibilities of fire hazards also be considered Proximity of site to railways/ roads should be considered (availability of fuels)

37. Pumping station Pumps can be placed above or below the sump water level Cast iron pipes using flanged joints are provided Velocity varies between 0.6-1.2 m/s at average flows Various valves are provided Gate valve Check valve Air valve Pumps of variable capacities are used so as to take care of the demand variation (peak, average) Stanby pumps are provided (in case of brake down)

38. Pumping station layout

39. Conveyance There are two stages in the transportation of water Conveyance of water from the source to the treatment plant. Conveyance of treated water from treatment plant to the distribution system.

40. Types of conduits Gravity flow system Flows freely due to gravity Pressure flow system closed conduits water flows under pressure above the atmospheric pressure.