Steam Condensers: Components, Types & Working Principle

In this article, I will share with you the components, types and working principles of steam condensers used in steam power plants.

Steam condensers are essential in steam power plants since they increase the power output by lowering the pressure of the exhaust steam.

There is a reason why these steam condensers are very important in steam power plants, and as you continue reading you will understand why they are put into use.

Steam condensers are used to receive the exhaust steam from the turbine or engine and then condense it resulting in a decrease in pressure of the exhaust steam lower than the atmospheric pressure.

The process of the condensers saves the steam power plant water and the amount of fuel used to heat the water.

With that introduction, let me now share with you what makes these steam condensers work.

For you to understand the working principle of the steam condenser, how to maintain it and how to operate it you have to know the main components of the steam condenser and how it works.

Main components of steam condensers

These are the main components of steam condensers;

Hot well; is where the hot condensate from the condenser is collected.

Tubes or pipes; are used to convey the cooling water and the exhaust steam around the condenser system.

Cooling water; is the cooling medium that is circulated within the condenser via the circulating pump or condenser cooling water pump.

Condenser cooling water pump; this is the pump that is used to pump the cooling water from the source to the condensers.

Air extraction pump; this pump is used to extract air continuously from the condenser to maintain a vacuum within the condenser.

Boiler feed water pump; this pump is used to provide feed water to the boiler.

Make-up water pump; this pump is used to pump water to the cooling pond to replace the water lost through evaporation or wind.

Condensate pump; this pump is used to remove the condensate from the condenser.

Types of steam condensers and their working principle.

There are two types of steam condensers used in steam power plants, these are;

Surface steam condensers.

Jet steam condensers.

1. Surface steam condensers.

From its name, the exhaust steam doesn’t come in contact with the cooling water.

The exhaust steam is passed over the tubes of cooling water, it gets condensed and the condensate is cooled and circulated again within the condenser.

This makes the surface steam condenser so economical since the condensate can be reused again within the condenser.

The surface steam condensers are further divided into three categories depending on the position of the condensate extraction pump, the flow of condensate and the arrangement of tubes.

These are the classification of the surface steam condensers;

Downflow surface steam condenser.

Central flow surface steam condenser.
Evaporation surface steam condenser.

1. Downflow surface steam condenser working principle.

The exhaust steam and air from the turbine or engine enters the condenser through the top part and flows down through the tubes carrying cooling water.

The steam flows in one direction, and that is down. The lower half of the air and exhaust steam goes out of the condenser in the opposite direction where there is an outlet provided by the side of the condenser and the remaining part of the exhaust steam and the air is condensed to condensate that is extracted by the condensate pump.

The condensate exists from the condenser through the bottom outlet that is provided by the down flow surface steam condenser.

2. Central flow surface steam condenser working principle.

In this condenser, the exhaust steam and air from the turbine or engine flow through the top part of the condenser.

The tubes carrying cooling water form passages that allow the exhaust steam to flow through them.

The air is pumped out from the centre of the condenser to allow the exhaust steam and air to flow towards the centre for maximum cooling.

This makes the condensate flow radially towards the centre of the tube nest.

As the steam moves towards the centre, it meets the under-cooled condensate that flows to the centre too and pre-heats it thus converting it to steam again, this reduces under-cooling within the condenser.

The condensate pump then extracts the condensate through the bottom tube of the condenser.

3. Evaporation surface steam condenser working principle.

This steam condenser work by the principle of evaporation to cool the exhaust steam.

This condenser has a circulating pump, a series of tubes and a make-up water pump.

The exhaust steam from the turbine or engine to be condensed is passed through a series of tubes and the cooling water is sprayed over the pipes carrying the exhaust steam.

This water that is sprayed over these pipes increases the cooling rate by evaporating with the heat of the exhaust steam into the environment.

Also, a stream of air flows over the tubes or pipes to enhance the evaporation of cooling water which further increases the condensation of the steam.

The condensate is extracted from the series of tubes or pipes by the condensate extraction pump and recirculated again for reuse.

Since a lot of water is lost through evaporation make-up water is added to replace the lost water.

Advantages of surface steam condensers.

These are the advantages of using surface steam condensers;

With surface steam condensers you can reuse the condensate as a feed water boiler since it doesn’t come in contact with the exhaust steam, thus saving water used in the steam power plant.

The cooling water used in surface steam condensers doesn’t have to be of good quality since it doesn’t come in contact with the exhaust steam.

The surface steam condensers offer a high vacuum of about 73.5 cm Hg thus higher thermal efficiency is obtained by using these steam condensers.

Disadvantages of surface steam condensers.

Despite the excellent working efficiency of the surface steam condensers they also have their limitations.

These are some of the disadvantages of surface steam condensers;

The capital cost of the surface steam condensers is higher due to the expenditure on the materials used to build them.
The maintenance and operation of the surface steam condenser are higher due to more parts and auxiliaries used in this condenser.

Since surface steam condensers have more parts they are bulky and occupy more space.

If you are thinking of using surface steam condensers then you should ensure that you have enough space in your plant to accommodate it.

2. Jet steam condensers.

Jet steam condensers are quite different from surface steam condensers since the cooling water in jet condensers comes in contact with exhaust steam while in surface steam condensers the exhaust steam flow over the tubes carrying the cooling water.

The water from the jet condenser can’t be reused in the boiler because it will have impurities that will end up decreasing the efficiency of the boiler.

These are some of the jet steam condenser components;

The nozzles or distributors; are used to distribute the cooling water within the condenser.

Steam inlet; is the part that allows the exhaust system to enter the condenser.

Mixing chambers; are used for mixing the cooling water and the condensate from the exhaust steam.

The mixing chambers may be of parallel flow type of counter depending on the flow of the condensate and the cooling water.

Hot well; is the place well the condensate and the cooling water are collected after mixing up.

Jet condensers are further categorized into two;

Low-level jet steam condenser (parallel flow type).

High-level jet steam condenser (Barometric jet steam condenser).

1. Low-level jet steam condenser working principle.

The working principle of the jet steam condenser of the parallel flow type.

In this condenser, the exhaust steam from the engine or turbine enters the condenser through the top part and the nozzles that are supposed to spray or distribute cooling water in the condenser are placed at the top part of the condenser too.

When the steam and air enter the condenser the cooling water is sprayed and it mixes with the exhaust steam hence condensing it.

The air within the condenser is removed by the air extraction pump and its outlet of the extraction is at the top part of the condenser.

The condensate and the cooling water mixture are extracted out of the condenser by the condensate pump.

The condensate extraction point is at the bottom of the condenser.

In the counter flow type jet steam condenser; the cooling water flows downwards while the exhaust steam from the turbine or engine flows upwards.

This is the main difference between the parallel flow type of jet condenser and the counter flow type of jet condenser.

2. Barometric jet steam condenser (high level) working principle.

In this jet condenser, the condenser shell is placed at a height of 10.33m which is the barometric height above the hot well.

This is to allow free flow by gravity, of the condensate and injection of water into the hot well.

The exhaust steam enters the condenser through the steam inlet provided on the upper side of the condenser, and the injection pump (a pump that provides cooling water (injection water) to the condenser) provides water to the condenser on the opposite upper side of the condenser.

The cooling water mixes up with the exhaust steam, it gets condensed and it flows out of the condenser through a tailpipe that is connected at the bottom of the condenser.

The condensate and cooling water mixture are collected at the hot well via the tail pipe.

When the hot well is full the condensate will overflow and it will be directed to the cooling pond where cooling will take place,

After the condensate is cooled the injection pump will pump it to the condenser to be reused.

You have to remember that the condensate isn’t taken to the boiler, it circulates only within the condensation system.

Ejector steam condenser working principle.

This is also a jet condenser that is quite different in the working principle.

The ejector steam condenser has the following components;

Non-return valve.
Converging cone.
Diverging cone.

Water inlet.
Steam inlet.
Condensate discharge line.

In this jet condenser, the cooling water is discharged under a head of 5 to 6 metres through the series of cones that are arranged within the condenser.

The exhaust steam enters the condenser through the steam inlet that is on the upper side of the condenser. The steam inlet contains a non-return valve to prevent the steam from escaping back to the turbine or engine.

The injection water (another name for cooling water used in the jet condenser) enters the condenser through the top part of the condenser.

When the injection water mixes with the steam pressure energy is partially converted into kinetic energy at the converging cones, which is the first cone that will accommodate the condensate and the injection water.

As the condensate and injection water flows down in the diverging cone from the converging cone the kinetic energy that was first created in the converging cone is converted again to pressure energy.

The condensate and the injection water are discharged under pressure to the hot well via the extraction point that is at the bottom of the condenser.

The main disadvantage of using jet condensers is that you won’t be able to use the condensate in the boiler, and this is a waste of water.

The advantage of the jet steam condensers is that they occupy a small space, are easy to maintain and they are compact.

Thanks for reading, if you have any questions or any additional points kindly leave your comment.