Working Principle Of Surge Tank

Working Principle Of Surge Tank

In this article, we will learn about the Working Principle Of Surge Tank. When the turbine is operating under the same load, the water in the pipeline will be uniform and have a pressure gradient. Due to the frictional loss in the pipeline, the water level in the surge tank is lower than that of the reservoir.

head of loss to friction in pipeline = OA ‘
Operating head = C’A ‘

As the load on the turbine decreases, the speed of the turbine tends to increase. Now the governing mechanism closes the turbine gate and stabilizes the turbine speed. Thus, excess water goes into the rejected water surge tank and elevates the water level in the surge tank above the reservoir level. Thus, the surge tank stores the retarding head (pressure). This is shown by the pressure gradient line OBB ‘.

Retarding head = A’B ‘.

When the turbines load too much, the turbine’s speed tends to slow down. Now the surge tank is supplying water to the turbine with the water coming from the penstock to reach the initial level of OAA. This creates an acceleration head in the surge tank. This refers to line occasions.

Acceleration head = A’C ‘

Types of Surge Tank:

Below are three commonly used surgical tanks.

1. Simple Surge Tank
2. The restricted orifice surgeon tank
3. Differential surgeon tank.

1. Simple surge tank:

It is a steep, circular-shaped reservoir. The small pipe is fitted with a penstock pipe. The water is slowly moving from the surgeon tank to the penstock pipe or from the surgeon’s tank to the penstock pipe. Doing so will result in more heat loss. In accordance with the turbines z_bite load conditions, the surgeon tank develops retarding and accelerating heads.

So that the speed of water will slow or decrease in the penstock pipe. In this system, the internal tank must be in high capacity. Otherwise, this setting will give you more pressure differential. So that this setting is avoided.

2. Restricted orifice surge tank:

It’s like a simple surgeon tank. But the surgeon tank is attached to the penstock by a small orifice. Its structure is shown. When the turbine load decreases, excess water enters the tank through the orifice and stores the retarding head. This is equal to the head loss in the pipeline. When loading on the turbine, the surgeon enters the penstock pipe through the orifice of the tank and produces an acceleration head.

Thus, acceleration and retardation heads are rapidly generated by this system. So unlike a simple surgeon tank, the amount of water stored and the amount of running water is less. So that the lower level tank is sufficient. Because of that, the cost is reduced.

3. Differential Surge Tank:

The tank is a cylindrical tank with a central riser in the center. Its structure is shown. Risers’ cross-sectional area is equal to the area of ​​penstock pipes. There are many ports in the orbit of the bottom of the Riser. When the load of the turbine is low, a low volume of water passes through the port into the surgeon tank. At the same time, excess water rises in the riser and flows into the tank.

Thus saving excessive retardation head. When the load is high on the turbine, the water level in the riser first drops, creating an accelerating head in less time. At the same time, water from the surgeon tank will slowly flow through the ports to the riser. This surgeon has the following advantages over other surgeon tanks.

1. Design is easy.
2. A tank with low capacity is sufficient
3. Water is not wasted.

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