Cepis

Health and Humor

Water Quality, Sanitation Technology for the Americas

 

HDT 51a: Pumping water with non-conventional energy

Eng. David Chavez Muñoz, professor at the Pontifical Catholic University of Peru, Resident at CEPIS. September 1992.

Spanish version: HDT 51a: Bombeo de agua con energias no convencionales

Hydraulic energy Equipment

Ram pump

The hydraulic ram pump is a simple machine that allow to raise a water flow q, to a height h greater than the height or fall H which constitutes the power supply of the pump. Its operation takes advantage of the tremendous pressure of the phenomenon known as hydraulic water hammer generated by the violent valve closure. For this, a flow Q (greater than q) enters the pump and is spilled, activating the valves, that the pump has for this purpose (2).

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  1. Features:

There are sizes varying from 2 “(50.8 mm) in the supply pipe to 20” (508 mm) in the biggest model. They can rise flows up to 60 l/s. The maximum pumping height is approximately 300 m.

  1. Applications:

It adapts easily for pumping water from the lower parts of the valleys to the upper parts.

It is ideal for pumping water where can be obtained waterfalls “H” (over 1 m), either from a spring, canal, ditch, stream, or from a river.

  1. Selection:

The right size for a necessity is selected according to the relation of the heights h / H and flow to be lifted. The following should be considered:

Q = Availability of water (m3/s) H = maximum falling height (m) h = Height of pumping (m) q = Water quantity raise (m3/s) l = Pumping distance (m).

  1. Costs:

EC: Varies between US $ 200 and US $ 25,000.

IC: Approximately 10% of CE.

MC: Approximately 5% of CE.

OC: Under $ 100.

Turbo pump

The system consists in the coupling of a turbine of the Michell-Banki type to a centrifugal pump (3). The wide application of these systems may include the direct generation of electric mechanical power (mills, sawmills, etc.).

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  • Features:
    • They can be built with materials and technology of low-cost in garages.
    • Takes advantage of springs, rivers or streams with flows from 30 to 1500 liters per second.
    • Work with jumps “H” of 2-25 m.
    • It Pumps up to 60 m and 70 l/s or produce electricity with power up to 60 kW with a performance of 55%.
  • Applications:

Are especially suited for pumping water from the lower parts of the valley to the highlands, and can simultaneously generate electricity with pumping.

  • Selection:

If in a river or a spring, there is a certain amount of water Q (m3/s) and a given falling is available H (m), can be selected the equipment of the turbo pump by the following procedure:

The maximum flow rate in l/s that could be pumped by the equipment is calculated by:

Q.(H-L)
q = ———— . 550
h + 0,05.L

where:

q = pumping flow h = height of pumping  (m) L = length of pumping (m)

Example: If Q = 500 l/s; H = 11 m; h = 40 m; L = 80 m is obtained q = 62 l/s.

  • Costs:

The turbo pump does not have standardized sizes and must be calculated for each installation. The approximate costs are:

EC: US $ 1,200 x kW of power.

IC: 10% of CE.

MC: 7% of CE.

OC: Under US $ 100.

River pump

The river pump is a machine composed of a free stream waterwheel and an alternative piston pump (4). The wheel takes the kinetic energy of the water flowing in a river, stream or canal with a small slope. Using a rod-crank mechanism, the rotation of the wheel is transformed into alternative linear motion to drive the reciprocating pump that lifts water from the river to the desired discharge level.

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  1. Applications:

It is an alternative solution to the problem of lifting water when there is no possibility of applying a pumping system based on falling water as an energy source. In these cases, the water flowing in a river, stream or canal, has little slope and does not allow the installation of a ram pump or a turbo pump. It is also feasible to simultaneously  generate  electricity or drive other mechanical equipment with pumping water.

  1. Selection:

The main dimensions of the wheel (diameter and width) depends on the water velocity as well as the cross section of the canal or river and the amount of water to be pumped. According to the analysis of the prototype, the power is calculated by:

Pot = 0,41 . V3. A

where:

Pot = Power of  turbine (kW) V = River speed (m/s) A = Cross sectional area of the hydraulic wheel (m2).

From this, the piston pump can lift a quantity of water q (m3/day) to height h (m) according to:

q . h = 8800 . Pot

For example, if V = 1 m/s, A = 0.5 x 1.4 = 0.7 m2, then: Pot = 0.287 kW and according this q x h = 2525. For a height of h = 20 m is obtained 126 m3/day.

  1. Features:

For standardized models:

  • Wheel Diameter: From 2.40 to 6.0 m.
  • Wheel Width: From 1.40 to 6.0 m.
  • Dimensions of the pumping system:
    • Standardized diameters of 2 1/2 “, 4”, 6 “and 8”.
    • Standardized strokes of 10, 20, 30, 40, 50 and 60 cm.
    • Maximum pump flow 20 l/s, minimum: 0.5 l/s.
  1. Costs:

Depends on the specifics of each installation. Can be approximated as:

EC: Approximately US $ 1,500 x kW.

IC: 20% of EC.

MC: 5% of CE.

OC: Under $ 100.

Wind pump

This machine transforms wind energy into mechanical energy. This is achieved by a rotor that turns by the drag of the wind speed (see Figure 4). Through a rod-crank transmission is powered a piston pump, that at the same time lifts the water (5).

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  1. Features:

The MCTB500 wind pump, developed by the Group, is of an American multiblade type with a  12 blades rotor and 5 m in diameter. Its nominal rotation speed is 30 rpm. Has an aerodynamic profile and a steel shaft transmission AISI-SAE 1020, with sealed ball bearings and an adjustable rod. The tower is 7 m high and has a rotating turntable with a steerable control by vane. Has an automatic brake (lever type). A reciprocating pump (piston) with damping chambers.

  1. Applications:

This wind pump can lift water up to a maximum height of 20 m. The maximum flow that can be obtained from this equipment is 4 l/s. Therefore it can be used to draw water from underground wells or to lift water from ponds to higher levels.

  1. Selection:

It is illustrated with an example: If the average wind speed for 6 hours is V = 5 m/s and want to extract water from a 15 m depth, the flow that will be extracted: 1.8 l/s 7 m3/h. Therefore, in 6 hours, 42 m3 will be pumped. Alternatively can be used the following formula for the power in Watts:

Pot = 0,078 . D2 . V3

Being D the rotor diameter in m and V wind speed in m/s.

  1. Costs:

Are variable with each installation site.

EC: Between US $ 2,700 to US $ 6,000.

IC: 15% of the CE.

MC: 15% of the CE.

OC: Under $ 100.

Wind Turbines

Wind turbines produce electrical energy through a two-stage process. The first is capture wind energy and transform it into mechanical energy through an aerodynamic rotor. The second step transforms mechanical energy into electrical on a synchronous generator. The electrical energy then passes through a voltage regulator, which corrects variations produced within this and allows its storage in batteries (6). The current coming from the batteries is distributed over two circuits. One is direct current and has the capacity to power the lighting circuits and all those appliances that have ohmic resistances. The second circuit is connected to an inverter that changes the direct current into alternating, and increases the 12, 24 or 36 volts from the battery to 110 or 220 volts.

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  1. Applications:

The electrical power which the wind turbine can supply, allows to power a variety of low consumption electrical appliances, including electric pumps up to 1/2 HP. Thus, water can be pumped either from underground wells, or from the surface to higher levels.

  1. Features: Referred to WAIRA Turbine:
    • Bladed rotor of 3 m in diameter, made of hybrid material (fiberglass/polyester/epoxy) with a NACA 4412 aerodynamic profile for 300 RPM.
    • Multiplication transmission belt and aluminum-silicon pulleys.
    • Synchronous generator with complete rectification  and inbluilt voltage regulator of 12 or 24 volts.
    • Steel profiles tower of 6 m.
    • Inverter for converting 12 or 24 volts stored in batteries to 220 V.
    • Batteries that depending on the size, can work up with 2,000 W continuously throughout the day (if there is wind 24 hours).
  2. Selection:

The power supplied depends on the wind speed according to:

Power = 1225 V3

where V = wind speed (m/s).

According with this, for winds of 10 m/s we can obtain powers of 1225 allowing the operation of centrifugal pumps (electric pumps) of up to 1.2 HP that provide a flow rate q of up to 6 m3/h at a height of h = 20 m. Thus, the generation of electricity from wind energy is an alternative to the problem of pumping.

  1. Costs:

EC: Waira Model 3.0 US $ 1,500.

IC: 5% of CE.

MC: US $ 200.

OC: Under $ 100.