Water Cooling System

Operational hydraulic turbine in a small hydroelectric power station is supported by an ancillary equipment such as:
* cooling water systems
* Lubrication system
* diesel generator for backup power
* fire extinguisher system
* and others

As an ancillary equipment, its design have a major influence on the reliability of operation, cost and efficiency of generating plant thus required accuracy in execution of design including design of the cooling water system for turbines to be delivered. This is often overlooked including the design made ​​by the manufacturer of the installation of generators, especially in small-scale hydropower development.  
May be useful.

Sources of water that can be used
Cooling water systems used for micro power plants. for thrust bearings, guide bearings, oil cooling system for lubrication, gearbox oil cooler system and governor.
Basic requirement is to satisfy the amount of supply which are the source of water can be obtained from the various alternatives as follows:
** Pumped from tailtace  
** Tapped from penstock  
** Taken from the turbine-cover

1. Pumped from tailtace

Pumping from the tailrace requires two sets of pump / turbine units (one in operation and the other as a backup) and a power supply with appropriate capacity. System suitable for the micro power plants that operate with clean water quality.

The downside of this system is that if water quality is less clear where the water content of many carrying garbage or mud so this system requires an automatic filter.

And at the time of flooding, pump and filter clogged by trash and silt and this could potentially cause problems.

2. Tapped from penstock
 

Cooling water from the penstock tapping is the best choice for micro power plants with a low head.
The important thing to note is  pipe hole position for tapping a hole-making in general. Location on the side of the penstock pipe to minimize the occurrence of blocking, because if it is placed on top, it tends clogged by floating trash and when placed under the hole in the pipe can clogged with mud or other trash.
On small-hydro power plants with a medium head up micro power plants with a high head, careful design is very important because the existing hydraulic pressure will be higher than the hydraulic pressure in the system
Here are some ways that decrease can be done to address:
* For medium head (<30 m), can be used valves.
* For higher energy-dissipator can be used.
The main drawback of this system is that there is a reduction of discharge water entering the turbine so as to reduce the production of energy from the micro power plants.
For example:
A kapasitas100 MW Hydropower and head of 100 m would require about 150 l / sec. cooling water. This causes a loss of about 130 kW. If the power is worth 10 cents / kWh, then the revenue loss would be in the range of U.S. $ 50,000 to $ 100,000. / Year. Losses can be reduced by controlling the flow of water through the generator cooling system in accordance with the temperature outside.

3. Tapped from turbin cover

For small-hydro power plants that use Francis turbines, water leaking through the seal runner-labirynth into the top cover can be used for cooling. Lots of experience, this way the simplest and most efficient way to get a supply of clean water as a source of cooling water, and can be used. Labyrinth seal leakage through a gap about 0.8 mm is about 0.5% of the water flowing through the turbine and the water is already filtered. A 100 MW turbine at the head of 100 m will have a leakage flow of approximately 500L / s, which is more than adequate for the needs of 150lt/sec. cooling.




4. Water Supply System
Provided for the turbine and generator equipment, consisting of 'automatic rotary strainer with an electric motor drive, including the installation of pipe complete with valves, flanges suport and other necessary equipment.
Capacity strainers are used in water supply systems must be able to meet the needs of both as well as cooling water sistem'sealing water '. Strainers should also pempunyai water supply capacity in the same amount despite the 30 percent of the system to crash with a pressure difference of not more than 0.3 kg/cm2.
Elements of the strainer is made of bronze or stainless steel with an aperture no larger than 3 millimeters and easy to clean by means of 'back-flushing'. The system includes a connection mounted strainers and valves required for operating, maintenance or operation for 'back-flushing', in each of the strainer system either on the exit side masukmaupun given pointing device pressure valve fitted. To clean the strainer element is done by turning towards the opposite or complement scraper tool (rotating scrapers) without disturbing the operation of the system. Driving force of the strainer system is activated automatically using a timer that can be set by means of a cycle time of 1-hour to 48 hours with 1-hour levels, and cessation using limit switches. Strainer system is also equipped with manual equipment to be used for operations during an emergency.