Showing posts with label steam turbine. Show all posts
Showing posts with label steam turbine. Show all posts

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

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

Read more on>>>>>>powerplant and calculations

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 1st stage ejector drain line and float trap in 2nd 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.


Read more>>>>powerplant and calculations


11-steps for steam Turbine major overhauling

 Major overhauling of a steam turbine is a comprehensive maintenance process that involves disassembling, inspecting, repairing, and reassembling various components to ensure the turbine's optimal performance and reliability. This process is typically carried out after a certain number of operating hours or as part of a scheduled maintenance program. Below are the key steps involved in a major overhaul of a steam turbine:


  • Develop a detailed overhaul plan, including a schedule and a list of required resources.
  • Ensure all necessary safety precautions are in place.
  • Secure the necessary permits and approvals for the overhaul.

2-Shutdown and Isolation:

  •  Safely shut down the steam turbine in accordance with established procedures.
  • Isolate the turbine from the steam supply and electrical systems.


  • Remove the outer casing and insulation.
  • Disassemble the various components, such as rotors, blades, diaphragms, and seals.
  • Inspect each component for signs of wear, damage, or corrosion.


  • Perform thorough inspections using various techniques, such as visual inspection, dye penetrant testing, magnetic particle testing, and ultrasonic testing.
  • Measure clearances and tolerances to ensure components meet specifications.
  • Assess the condition of bearings, gears, and other auxiliary components.

 5-Repair and Replacement:


Repair or replace damaged or worn components.

Balance rotating elements, such as the rotor, to ensure smooth operation.

Recondition or replace seals and gaskets.




Clean all components thoroughly to remove dirt, debris, and deposits.

Use appropriate cleaning methods, such as steam cleaning, chemical cleaning, or abrasive blasting.




Reassemble the turbine components according to the manufacturer's specifications and tolerances.

Ensure proper alignment and fit of all parts.


8-Testing and Commissioning:


Conduct functional tests to ensure proper operation of the turbine.

Perform performance testing to verify that the turbine meets specified efficiency and power output.

Address any issues identified during testing.




Document all maintenance activities, including inspections, repairs, and tests.

Update maintenance records and logbooks.



Gradually bring the turbine back into operation, closely monitoring performance.

Address any issues that arise during the startup process.


11-Post-Overhaul Analysis:

Evaluate the success of the overhaul and identify areas for improvement.

Implement any recommended changes to the maintenance program.

 For more >>>>articles read powerplant and calculations

What is the difference between condensing cum extraction Turbines and back pressure turbines??


SL No.

Condensing cum extraction Turbine

Back pressure Turbine



In a condensing turbine, steam is expanded in the turbine until it reaches a very low pressure, and then it is condensed back into water.

In a back pressure turbine, steam is expanded in the turbine until it reaches a predetermined pressure, known as the back pressure.



The condensation of steam at the turbine exit creates a vacuum, which increases the efficiency of the turbine by lowering the back pressure.

The exhaust steam from the turbine is released at a higher pressure, and it is often used for industrial processes where both power and heat are required.





Condensing turbines are often used in power plants where the objective is to maximize the power output from the steam and achieve higher efficiency. The condensed water is usually returned to the boiler for reuse.

Back pressure turbines are commonly used in combined heat and power (CHP) systems, where the steam is extracted at different pressures for various industrial processes, and the remaining steam is allowed to expand through the turbine to generate power.




Condensing cum extraction turbines generally provide higher overall efficiency compared to back pressure turbine.

The combination of condensation and extraction processes allows for better utilization of the available energy in the steam.

Lower over all efficiency


More power out put at same steam inlet

Lower power out put

Power out put reduces by 4 to 5% at same inlet steam flow.


No much effect on power generation if extraction steam consumption reduced, since this steam can be diverted to surface condenser

Power consumption reduces if exhaust steam consumption reduces, since there is no any option to expel the steam to generate power.


Lower temperature of extraction steam around 145 to 155 deg C

High exhaust temperature around 150  to 175 deg C, which is loss


Power can be generated even at no or minimum extraction

Constraints in power generation during no or minimum extraction


Or steam needs to be vented out if electrical power requirement is more.


Auxiliary power consumption of the plant is little bit higher for handling cooling water pumps and cooling tower fans

Auxiliary power consumption is lesser since there is no condenser and hence no cooling water pumps and fans


Initial cost of the project is more due to surface condenser, cooling tower and cooling water pumps

Cost of the project is less as compared to condensing turbines


Heat rate is comparatively more

Heat rate is less since there is no loss of heat in condensers


Operation is little bit critical

Simple operation


Limited extraction steam flow

Exhaust flow will be more since there is no condenser and same steam can be diverted to process as exhaust steam


Read more >>>>on Powerplant and calculations

What is the function of Balance piston in steam Turbines???


In a steam turbine, a balance piston is not a dummy piston but rather a real and essential component designed to improve the efficiency and performance of the turbine. A balance piston is used in certain types of steam turbines, particularly in reaction turbines, to help maintain axial balance and reduce the axial thrust force on the rotor.

A steam turbine consists of a rotor with blades attached to it. Steam is directed onto these blades, causing them to spin. As the blades turn, they exert a force on the rotor in the axial direction, along the length of the rotor.

Here's how a balance piston works in a steam turbine

Role of Balance Piston:

Steam turbines are designed to convert the energy of high-pressure steam into mechanical rotational energy, which is then used to generate electricity or perform other mechanical work.

During the operation of a steam turbine, steam enters the turbine blades or buckets and expands, creating a force that drives the rotor in a rotary motion.

However, this expansion of steam also generates an axial thrust force along the length of the rotor. This axial thrust force can be significant, especially in larger turbines.

Purpose of balance piston

To counteract the axial thrust force and prevent excessive axial movement of the rotor, a balance piston is often used.

The balance piston is typically located at the opposite end of the rotor from the steam inlet. It is exposed to the same steam pressure as the turbine's inlet.

The balance piston is attached to the rotor, and its movement is opposed by a set of springs or hydraulic systems.

How balance piston Works:

When high-pressure steam enters the turbine and imparts a force on the rotor blades, it also exerts an equal and opposite force on the balance piston.

This opposing force on the balance piston helps to balance out the axial thrust force generated by the steam expansion on the other side of the rotor.

The balance piston essentially acts as a hydraulic or mechanical counterbalance, minimizing the net axial thrust force on the rotor.

The pressure acting on the dummy piston generates an equal and opposite axial force. This force counterbalances the axial thrust generated by the turbine blades. By adjusting the pressure on the dummy piston, operators can control and balance the axial forces within the turbine.

Why balance piston is required:

By reducing the axial thrust force, the balance piston helps to maintain the stability and longevity of the turbine.

It also reduces the wear and tear on the thrust bearings, which are responsible for supporting the axial load of the rotor.

Overall, the use of a balance piston contributes to the efficient and reliable operation of the steam turbine.

It's important to note that the design and location of balance pistons can vary among different types and manufacturers of steam turbines. While balance pistons are common in reaction turbines, they may not be present in all steam turbine designs.

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