6 Reasons Why Steam Temperature Fluctuate

In this article, I will share with you some of the reasons why steam temperature fluctuates during generation and conveying.


The temperature of the steam from the boiler will change for several reasons.


If you know anything about boilers and the process of steam generation, you already know that the temperature of the steam plays a big role when it comes to its effectiveness in operation.


In some cases, the drastic drop in steam temperature will lag the power plant process.


If the steam is to be used in a steam turbine, it won’t produce the necessary work needed.


The steam turbine mainly depends on the heat energy of the steam to perform the work.


You might like this: Steam Turbines: Function, Classification, Parts And Working Principle


So, it’s important to know why the steam temperature may fluctuate for one to know how to fix this problem.


There are some processes that require a supply of steam at a constant temperature.


A change in the steam temperature will affect the overall efficiency of the power plant or the process that uses the steam.


If we talk about a steam turbine; for it to perform work effectively the steam temperature and pressure should be constant during the supply.


Without wasting time, let me share some of the reasons why steam temperature may fluctuate.


This is why steam temperature fluctuates;

1. Variation of heat energy produced from the furnace.

The change in heat energy produced by the furnace is one of the first reasons why the steam temperature fluctuates.


reasons for steam temperature fluctuations

The variation of heat energy produced by the furnace influences the exact change in steam temperature.


At one point or another, the heat energy produced by the furnace is going to change during a charge of fresh volume of fuel.


When the fuel is burnt completely, there will be a need to add a fresh volume of fuel to the furnace.


This usually interrupts the constant continuous supply of heat energy from the furnace.


Since the moment a new volume of fuel is added to the furnace, it will take a while before the furnace reaches its initial temperature.


At this point, the steam generation process will be lower and the steam that will be produced will have lower thermal energy.


This is something that can be hardly avoided especially if pulverized coal is not used.


You might like this: Advantages Of Using Pulverized Coal


But with the pulverized coal, the initial temperatures of the furnace can be attained easily without a delay thus keeping the steam temperature where it was before it’s even released from the boiler.


2. Fluctuation in the quantity of excess air.

The excess air in the furnace plays a big role when it comes to the complete combustion of the fuel in the furnace.


You might like this: Conditions For Proper Burning (Combustion) Of Fuel


The maximum amount of heat will be produced from the furnace when there is a balanced quantity of excess air.


The excess air in the furnace facilitates every combustible material in the furnace to be burnt completely.


Complete combustion leads to the production of a great amount of heat thus increasing the steam temperature.


When there is a fluctuation of the excess air in the furnace, the steam temperature will also fluctuate because of the variation in the amount of heat energy that will be produced.


Now you get why the fluctuation of the excess air causes the fluctuation of steam temperature.


3. Variation in moisture and air temperature entering the furnace.

The variation in moisture content and air temperature entering the furnace is another reason why the steam temperature fluctuates.


You have to know that the air and moisture content entering the furnace affects the amount of heat produced.


If the air temperature entering the furnace is going to be higher, this will initiate complete combustion.


And that is why it’s necessary to use preheated air in the furnace for maximum efficiency.


The air preheaters will ensure that the temperature of the air entering the furnace is constant thus leading to a constant heat generation.


You might like this: Air Preheaters in Steam Boilers: Function, Types and Working Principles


This is what prevents the fluctuation of heat energy produced by the furnace.


But if there will be a variation in air temperature entering the furnace, it will be impossible to obtain steam with constant thermal energy.


The moisture content entering the furnace also affects the performance of the furnace.


If the moisture content temperature will be lower, the combustion rate will be lower thus affecting negatively the thermal energy of the steam.


Also, moisture in the furnace lowers the amount of heat that will be produced hence affecting the steam temperature.


Hopefully, you get what I am trying to explain here.


4. The variation of feed water temperature.

The feed water temperature also plays a big role when it comes to the fluctuation of steam temperature.


The steam to be generated from the boiler comes from the boiler feed water.


Usually, the boiler feed water has to be heated before it’s fed into the boiler for steam generation.


There are lots of benefits of heating boiler-feed water, it’s not only about increasing its temperature but also treating it.


You might like this: 4 Reasons Why Boiler Feed Water Needs To Be Heated


If the boiler feed water is fed into the boiler at a constant temperature while the other factors I have talked about in this article remain constant, then the steam temperature will hardly fluctuate.


But if the boiler feed water temperature keeps on changing because the boiler feed water heaters have an issue the temperature of the steam will always fluctuate.


You might like this: Feed Water Heaters: Functions, Types, Advantages And Operation


The feed water fed into the boiler has to be at a constant temperature for the steam temperature to be constant.


Any changes in the temperature of boiler feed water will affect the steam temperature significantly.


5. The varying condition of the surfaces that absorbs heat.

The surface absorbs heat that aids in heating the boiler is essential when it comes to steam generation.


If the heat surfaces are dirty (full of soot) there is no way heat transfer will be effective.


When this is the case the amount of heat supplied to the water in the boiler will not be sufficient.


At the start, the fireside may be clean, but as it’s continuously used, it needs to be cleaned and maintained.


This is what will keep the amount of heat supplied to the boiler constant.


But if it’s left dirty, the amount of heat that will be transferred to the boiler will be less compared to when the fireside surfaces were clean.


And this is what is going to cause the fluctuation of steam temperature.


6. Heat losses during distribution.

The steam produced from the boiler may not fluctuate at all because the conditions in the boiler are constant.


But when it comes to distribution the steam temperature will decrease because of heat losses.


Heat losses will occur in the distribution of steam lines due to radiation, convection and conduction.


And that is why lagging of the steam distribution lines is required to ensure that these heat losses are minimized.


Also, the distance at which the steam is supposed to be conveyed should be reduced if that is possible to ensure less amount of heat is lost.


Another thing one can do is by superheating the steam before it’s supplied to the point of consumption.


You might like this: Advantages Of Using Superheated Steam


Heat loss during the conveying process is one of the causes that fluctuates the temperature of the steam.


You might like this: Type Of Heat Losses In a Steam Plant (+How To Minimize Them)




Most of the reasons why steam temperature fluctuates are mainly because of the condition changes inside the furnace.


So, if you want to prevent fluctuation of the steam temperature you have to ensure that your furnace operates at a higher efficiency.


The other measures I have talked about you should also consider them if you want the best output from the boiler.


Thanks for reading, if you have any additional points you would like me to add or questions just leave them in the comment section.


See you in my next article.


Related articles to check.

  1. Characteristics Of A Steam Power Plant
  2. Steam Power Plant: Introduction, Components And Working Principle
  3. Properties Of Coal Selected For Steam Power Plants
  4. 6 Requirements Of a Steam Boiler
  5. Fluidized Bed Combustion (FBC): Types, Working Principle & Advantages and Disadvantages 

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