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The Complete Steam Guide
Famous mathematician Hero, also known as Heron was probably the first one to come with a simple steam engine. Hero from Alexandria, also wrote three books on mechanics and properties of air. This dates back to AD. 75.
Steam is largely used for the purpose of process heating. Using steam for processing heating offers multiple benefits over other heating media. Numerous benefits, simplicity of the system and high efficiency and reliability make steam the first choice for process heating.
Saturated steam is the steam which is completely dry and has same temperature as the water from which it is formed. When we start boiling the water, its temperature goes on increasing till it reaches the boiling point at that pressure.
This article elaborates on different grades of steam and characteristics of each of them.
Clean steam is defined as steam which is free of all kinds of contaminants. There are many different substances, which may be considered as contaminants; in general, they can be classified into four groups
Steam quality plays an important role in determining the quality of final product. At the same time, steam quality is also important to ensure smooth working of the plant and operational efficiency.
Flash steam is produced when high pressure condensate is discharged to a lower pressure. The word 'flash' describes the way it is formed. At atmospheric pressure, water boils at 100 Deg. C.
Heat flows from higher temperature to lower temperature. Though it looks simple, heat transfer is a quite complex phenomenon.
Heat energy is transferred on the virtue of temperature difference. So, when there are two bodies, with different temperatures in contact with each other
It is always advisable to use dry steam for heating applications. Dryness of steam is measured as expressed as dryness fraction.
When the heat from steam is transferred either to the product or to the surrounding, the steam condenses on the cold surfaces.
Combustion is a chemical process. It is a reaction between the fossil fuels such as coal or natural gas and oxygen.
A coil type boiler is water tube design, the water travels through the coil and is surrounded with flue gases.
It is a well known fact that the initial cost of boiler is a small part of total costs associated with the boiler over its lifetime.
The table below gives a brief comparison of Water Tube and Smoke Tube Boilers-
Most of the boiler failures can be attributed to low water conditions. For safe boiler operations this must be kept under check.
Safety and efficiency are always given a prime importance by both boiler manufacturers and steam users.
A boiler is an enclosed vessel that provides a means for combustion and transfers heat to water until it becomes hot water or steam.
Different types of boilers are available in the market, which are manufactured by different manufacturers.
In order to generate steam on a constant basis, boiler should be continuously supplied with water, called as feed water.
As all of us are aware, in a boiler, steam formation takes place because of heat transfer from fire side to water side.
The most harmful of the dissolved gases is oxygen, which can cause pitting of metal. Very small amount of oxygen can cause severe damage
Water softeners are specific ion exchangers that are designed to remove ions, which are positively charged.
Constant combustion takes place inside a boiler furnace. In order to burn the fuel, oxygen is required.
The method most standards (including IS8753, BS845 etc.) follow is the indirect efficiency calculation method.
As we are aware, boiler efficiency can be stated in two different ways, one being direct and another, indirect.
As we are aware, boiler efficiency can be stated in two different ways, one being direct and another, indirect
In case of boilers, cost of buying a new boiler is small compared to the amount of money spent in operating the boiler year on year.
Steam Pipes Sizing or Correct sizing of steam lines reduces pressure drop and radiation loss.
During start up the steam pipework is cooler than the steam. This leads to heat transfer from the steam to the pipe
When any solid, liquid or vaporous contaminant leaves the boiler drum along with the steam, the phenomenon is called as carryover.
Steam pressure is governed by certain factors as mentioned below:
Flushing of steam piping is an activity which is often neglected but can damage the components of steam system.
During the period of shutdown, steam and condensate are removed from the system and the space inside is occupied by air.
Water hammer is a commonly observed phenomenon taking place during a fluid flow. Presence of water hammer can be easily
Pressure reducing & de-superheating stations are used to reduce pressure and de-superheat the steam at the exhaust
In most of the industries, steam is used as a medium for transferring energy. Steam is generated by the combustion of various types of fuels.
Mechanical dust collectors, often called cyclones or multiclones have been used extensively to separate large particles from a flue gas stream.
Fabric filters, also commonly referred to as bag houses, are used in many industrial applications. They operate similar to a vacuum cleaner.
Electrostatic Precipitators (ESPs) are relatively large, low velocity dust collection devices. ESPs remove particles similar to that of static
Steam traps hold the steam and drain out the condensate. When in service, a steam trap has to perform against many odd conditions.
Stall in heat exchangers is one of the frequently faced problems while operating steam systems. The word stall literally means to suddenly stop working.
Ball valve is a quarter turn operated valve. The closure member is a spherical plug with a through hole. When the valve is in open state
In case of manually operated valves, human force is used to actuate the steam which in turn moves the closing element.
On-Off valve operates only in two modes- it is either fully open or fully closed. A tap to fill overhead tank is a good example of on-off valve.
A Steam Trap is an integral part of a steam system. Steam traps play the important role in maintaining the productivity and efficiency of steam system.
Air Locking impedes continuous evacuation of condensate and hence impedes heat transfer.
Correct installation of steam traps is as crucial as correct selection of steam traps. Many times, it has been observed that correctly selected steam traps often fail due to wrong installation.
Steam trap failure is a topic of worry for many plant managers. Failure of steam traps hampers the performance of steam system and is a safety hazard as well.
Finding out failed steam traps and fixing them up can avoid the wastage of steam and improve the productivity and performance of the steam system.
In addition to its widespread application in the above industries, steam trace heating is also used on a smaller scale by factories and docks etc.
Where the product temperature is critical, to prevent solidification of the product in the pipeline, or where the temperature of the product
Recovering condensate help in many ways. Following are a few benefits of recovering condensate and mixing it with make up water in a feed water tank-
The condensate if recovered and reused can be useful for the plant but if it is not treated appropriately can be hazardous to the maintenance of the plant.
The exact calculation of the line size would be complex and probably inaccurate due to the number of variables.
nlet pressure of the steam trap can be used as the driving force for transportation of condensate to the collection tank at positive differential pressure.
In a well maintained, properly operating boiler system, condensate is almost pure water with low conductivity and minimal dissolved solids.
Whilst it is desirable to return the maximum amount of condensate to the boiler, it is essential to ensure that it is clean.
Flow metering is very critical as it enables the users to monitor and hence control the use of utilities like steam, water etc.
In case of a fluid flow, the relation between volumetric flow and velocity of fluid can be defined as-
Positive displacement type flow meters divide the fluid in measured portions and then pump it.