Why do U loop is provided in 1st stage ejector drain lines?

 Why do U loop is provided in 1^st stage ejector drain line and float trap in 2^nd stage ejector drain line???

Pressure difference between first stage ejector condenser also called inter condenser and surface condensers about 0.25-0.35 kg/cm2 or 2.5 to 3.5 meter water head.In between 2nd stage ejector & surface condenser the pressure difference is so less that no other economic equipment is available other than U loop for sealing.

 

Further, pressure difference between 2^nd stage and surface condenser is around 0.85 to 1 kg/cm2, so there we can use float type condensate trap.This will  help in sealing for two different pressure & discharging of condensate

 

Other functions of U loop in ejectors

Read more>>>Why do U loop is provided gland steam condensers??

 

U-loops, or U-bends, are provided in ejector drain lines primarily for the following reasons:

 

1-Trap Formation:The U-loop acts as a trap to prevent back flow of gases or liquids. This is crucial in ensuring that the fluid or gas being ejected does not re-enter the system, which can lead to contamination or inefficiency.

 

2-Seal Creation:The U-bend helps to maintain a liquid seal. This seal can block the passage of vapors or gases, ensuring that they are properly vented or drained away from the system.

 

3-Pressure Management:In some systems, U-loops can help manage pressure differentials. They can serve as a barrier to equalize pressure between different sections of the system, preventing sudden pressure changes that might cause operational issues.

 

4-Thermal Expansion Accommodation:The U-loop can accommodate thermal expansion and contraction of the piping system. This flexibility helps to prevent stress and potential damage to the pipes due to temperature changes.

 

5-Maintenance and Inspection:U-loops can also facilitate easier maintenance and inspection. They provide a convenient location for installing inspection points, drains, or clean-out connections.

 

6-Trap Debris: U-loops can help in trapping debris and preventing it from entering the downstream components. This helps in maintaining the efficiency and longevity of the equipment.

 

7-Noise Reduction: The liquid seal in the U-loop can also act as a buffer to reduce noise and vibrations that might be transmitted through the piping system.

 

8-Pressure Regulation: U-loops can help in regulating pressure changes within the drain line. This can be important in systems where pressure fluctuations might otherwise cause operational issues.

Why do we exhaust gland steam in a second stage inter condenser and not in the main condenser?

There are three major reasons;

1-The gland steam system handles leakage steam from the turbine shaft seals, which prevents air from entering the turbine casing.

2-If this steam were exhausted directly into the main condenser, it could carry air and non-condensate gases, reducing the vacuum efficiency and lowering turbine performance.

3-The second-stage inter condenser removes these gases before they enter the main condenser, helping maintain optimal vacuum conditions.

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Why gland sealing is provided in steam Turbines??

 Significance of steam Turbine gland sealing system

 

 

A turbine gland sealing system is an integral part of steam turbine operation, essential for maintaining efficiency, protecting critical components, and ensuring safe operation.

 

Functions of gland sealing system:

 

Preventing Steam Leakage: 

The primary function is to prevent steam from leaking out of the turbine casing at the points where the rotating shaft exits the casing. This ensures the turbine operates efficiently by maintaining steam pressure and preventing energy losses.

 

Protecting Bearings:

 

It prevents steam from entering the bearing housing, which could lead to lubrication issues and potential bearing damage.

 

Maintaining Vacuum:

In condensing turbines, it helps maintain the vacuum in the condenser by preventing air from leaking into the system.

 

What are the components of gland sealing system???

 

Labyrinth Seals: These are non-contacting seals that use a series of ridges and grooves to restrict steam flow. They are effective at high speeds and temperatures.

 

Carbon Ring Seals:These seals consist of segmented carbon rings that provide a tighter seal than labyrinth seals, often used in low-pressure applications.

 

Steam Seal Regulator: This component regulates the amount of sealing steam supplied to the seals, ensuring an optimal balance between sealing effectiveness and steam consumption.

 

Sealing Steam Supply and Exhaust System:This includes the piping and control systems that manage the flow of sealing steam to and from the turbine gland areas.

 

Operation of the Gland sealing system:

 

Sealing steam is typically extracted from an intermediate stage of the turbine or through PRDSH station. It is introduced into the gland areas at a controlled pressure around  0.1 to 0.2 kg/cm2.

 

At HP side sealing steam helps to seal the glands there by preventing leakage of steam from inside to outside, whereas in LP side it prevents the ingress of atmospheric air in gland sealing system.

 

Any leakage past the seals is collected and returned to the condenser or reintroduced into the steam cycle, minimizing waste.

 

Why do U loop is provided in Gland sealing steam condenser drain lines?

 

Generally gland seal condensate drains are left to condenser hot well. The pressure difference in the condenser & gland sealing is very less, in order to seal this a small U seal say around 500 mm to 2 meters is provided in gland steam condenser drains.The U-loop helps maintain the necessary pressure differential across the gland seal system. By trapping condensate, it creates a barrier that ensures the pressure in the gland seal system is properly managed, which is critical for the system's efficiency and performance

 

Also U loop performs following functions.

 

The U-loop acts as a water seal to prevent steam or air from the gland seal system from flowing back into the drain line, which could lead to inefficiencies or potential damage to the system.

 

In systems where the condenser operates under a vacuum, the U-loop acts as a barrier to prevent air from being drawn into the system. Air ingress can reduce the efficiency of the condenser and the overall steam cycle.

Read more>>>>Why do U loop is provided in 1^st stage ejector drain line and float trap in 2^nd stage ejector drain line???

 

The U-loop ensures that condensate is drained in a controlled manner, preventing sudden surges of water that could potentially cause damage to downstream components or lead to operational issues.

 

The U-loop provides some flexibility for thermal expansion and contraction of the drain line. This reduces the risk of mechanical stress and potential failure of the piping due to temperature changes.

 

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