Difference Between : Hogging - sagging ,Pipe - Tubes ,IBR - Non IBR boiler,Cold end -Hot end corrosion - ASKPOWERPLANT

Difference Between : Hogging – sagging ,Pipe – Tubes ,IBR – Non IBR boiler,Cold end -Hot end corrosion

power plant terms

Difference Between : Hogging – sagging ,Pipe – Tubes ,IBR – Non IBR boiler,Cold end -Hot end corrosion

in this article we discussed difference Between : Hogging – sagging ,Pipe – Tubes ,IBR – Non IBR boiler,Cold end -Hot end corrosion these terms which related to power plant these terms  are very common  for who worked in power sector but these terms are little bit confusing . this article are cleared all the confusion about these terms .

Hogging and sagging:-

Hogging and sagging terms describe the shape of a beam when it is under loading or similar long object when loading is applied.
Hogging: – hogging describe when a beam which curve upward in the middle.
Sagging: – sagging when a beam bent during the loading and form downward curves. It generally happening in horizontal tubes and piping between supports.



Difference between pipe and tubes

Pipes:  a pipe is used for  the transport of a fluid like water, oil or similar, and the most import property is the capacity or the inside diameter.

Tubes: the tubes N.D (Nominal Dimensions) are based on the outside diameter. While inside diameter of a tube depends on the thickness of the tube.

Difference between IBR boiler and non IBR boiler

IBR BOILER: in IBR boiler is used for the steam generated for use external purpose  to itself by application of heat which is wholly or partly under pressure when steam is shut off but does not include a pressure vessel.

Non IBR boiler:-

1. With capacity less than 25 liters.
2. with less than one kilogram per centimeter square design gauge pressure and working pressure.
3. In which water is heated below one hundred degree centigrade.

Difference between natural draft and artificial balanced draft

Natural draft: – natural draft is the draft produced by a chimney alone. It is caused by the difference in weight between the column of hot gas inside the chimney and column of outside air of the same height and cross section. Being much lighter than outside air, chimney flue gas tends to rise and the heavier outside air flows in through the ash pit to take its place. Draft is usually controlled by hand operated dampers in the chimney and breaching connection the boiler to the chimney. Here no fans or blowers are used. The product of combustion is discharged at such a height that it will not be a nuisance to the surrounding community.

Artificial balanced draft: forced draft FD fan pushes air into the furnace and induced draft ID fan draws gases into the chimney thereby providing draft to remove the gases from the boiler. Here the pressure is maintained between 0.05 to 0.10 in. Of water gauge below atmospheric pressure in the cases of boilers and slightly positive for reheating and heat treatment furnaces.

Difference between steam injects soot blowers and sonic soot blowers

Steam inject soot blowers: – in this type of soot blowers steam is used as the cleaning medium. in the stam injector soot blowers steam flow through a pipe and nozzle, which is called lance at end of lance two nozzle are connected generally these nozzle are in the shape of hole which are drilled at the end of lance which create nozzle effect during operation strikes at the surface of tube and removes the soot. Here three soot blowers are generally used as
1. LRSB (Long retractable soot blowers)
2. Wall soot blowers
3. Rotary soot blowers

Sonic soot blowers:-

This type of soot blowers is used to removes soot by using low energy and high frequency sound. They produce high wavelength sound waves which hit at the surface of tube wall and remove the deposited soot. By using this type of soot blowers erosion and corrosion of tube can be avoided. Steam loss can also be avoided. The frequency of sound in this type of soot blowers is ranging from 60 HZ to 350 HZ.

Difference between cold end corrosion and hot end corrosion

Cold end corrosion: in power plant boiler is used for generating steam for use in power generation and process due to combustion of different type of fuels. These fuels contain sulfur to differing percentage.  higher the percentage of sulfur content in fuel, the higher will be the risk of cold end corrosion in the boiler. The sulfur in the fuel during combustion gets converted to sulfur dioxide. its also  depend upon the other impurities present in the fuel and excess air levels, some portion of the sulfur dioxide gets converted into sulfur trioxide.  Moisture is present in the flue gas due to moisture in fuel and air, sulfur dioxide and trioxide combined with moisture and forms sulfuric acid and sulfuric acid. These type of acids condense at the temperature of  115 degree centigrade to slightly higher than 160 degree, depending upon the tendency  of SO3 and water – vapor. The basic reaction taking place are

S+O2 – SO2
SO2 + O2 – SO3
H2O + SO2 – H2SO3
H2O + SO3 – H2SO4

the tendency of  ppm of SO3  presence  causes the acid  dew point and water vapor concentration,the dew point temperature can vary from around 90 degree centigrade to 140 degree centigrade condensation of these acids causes in metal errosion  and boiler tube failure due to reducing thickness of tubes , air preheater corrosion, and flue gas duct corrosion.



Hot end corrosion :

Same conditions also responsible for the  fireside ash corrosion , high temperature oxidation can occur locally in areas that have the highest outside surface temperature relative to the oxidation limit of the tube material. Determining  the real root cause factors between the mechanism of ash corrosion or high temperature oxidation is best done by tube analysis and evaluation of both ID and OD scale and deposits.


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