Today we are discussed about a very important post which is top 17 boiler question and answer you n never know in this article we are know about the important question answers of boiler in steam power plant operation . these boiler question answers boost up your power plant knowledge as well helped them who preparing for the BOE ( Boiler Operation Engineering ) , Energy Manager examination and also for who prepared the viva examination of boiler 1st class examination . These boiler question answers are selected by those peoples who passed the BOE , Energy Manager , Energy Auditor examination already . Let us discussed the top 17 boiler question answer you never know about it .
Q1. What are the data required for calculation of boiler efficiency by using ‘indirect method’.
The data required for calculation of boiler efficiency using indirect method are:
>Percentage of Oxygen or CO2 in the flue gas
>Flue gas temperature
>Ultimate analysis of fuel (H2, O2, S, C, moisture content, ash content)
.> GCV (Gross Calorific Value) of fuel in kcal/kg
>Percentage combustible in ash (in case of solid fuels)
>GCV(Gross Calorific Value) of ash in kcal/kg (in case of solid fuels)
>Ambient temperature in 0C (Ta) & humidity of air in kg/kg of dry air
Q2. What are the ways of reduction of steam usage?
– By reduction in operating hours
– By reduction in steam quantity required per hour
– By use of more efficient technology
-By minimizing wastage
Q3. What is the limitation of ‘direct method’ of boiler efficiency calculation over ‘indirect method’?
In Direct method following limitation we are calculating the efficiency of boiler
a) It’s not provide the any idea for the operation persons as to why efficiency of system is lower
b) Do not calculate various losses accountable for various efficiency levels
Q4. What are the important precautions to be taken while construct a flash vessel for flash steam recovery system?
> When we are designing the flash vessel for steam recovery system the diameter of the vessel should be such that large amount of velocity drop allows the condensate to fall to the bottom of the vessel from where it is drained out by the steam trap
> Flash steam itself rises to leave the vessel at the top
> Flash vessel height should be sufficient enough to avoid water being carried over in the flash steam
Q5. What do you meant by tangential firing in boiler with respect to pulverized coal fired boiler?
The method of firing used for coal firing in pulverized fuel fired boiler is the tangential firing. In tangential firing four burners are used at the corner to corner to create a fire cyclone at the center of the furnace which helps the uniform heat up the furnace water valve panel.
Q6. What are the advantages of direct admission of steam for heating of liquid?
The equipment required is relatively simple, cheap and easy to maintain
No condensate recovery system is necessary
The sensible heat in the steam is also used up along with the latent heat, because of it quick heat-up properties so it making the system thermally efficient
Q7. What are the different types of heat losses occur in a boiler?
The principle heat losses that occur in a boiler are:
-Loss of heat due to dry flue gas
– Loss of heat due to moisture in fuel and combustion air
– Loss of heat due to combustion of hydrogen
-Loss of heat due to radiation
-Loss of heat due to unburnt fuel
Q8. What are the two common causes of wet steam formation in a steam generation and distribution network?
The two most common causes of wet steam formation are:
Generation of steam in a boiler without a super heater
Effectiveness of lagging of steam distribution pipelines
The wetness in steam is removed by providing steam separators or cyclone separators and steam trap at suitable locations
Q9. What is the effect of boiler loading on boiler efficiency?
The maximum efficiency of the boiler does not occur at full load, but at about two-thirds of the full load. If the steam load on the boiler decreases so that the efficiency also tends to decrease.
As the load reduced, so does the value of the mass flow rate of the flue gases through the tubes. This decreases in the steam flow rate for the same heat transfer area reduced the exit flue gas temperatures by a small extent, reducing the sensible heat loss. Below half load, most combustion appliances need more excess air to burn the fuel completely. This increases the sensible heat loss.
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Q10. Define latent heat of vaporization of fluid?
Latent heat of vaporization of fluid is the quantity of heat required to change a fluid from the liquid to the gaseous state is called latent heat.
Q11. What is the principle of mechanical deaeration (pressure type) of boiler feed water?
The mechanical or pressure-type de-aerators operates by allowing steam into the feed water through a pressure control valve to maintain the desired operating pressure, and hence temperature at a minimum of 105 °C. The steam raises the water temperature causing the release of O2 and CO2 gases that are then vented from the system. This type can reduce the oxygen content to 0.005 mg/litre.
Q12. Give any three functions of steam trap?
Steam traps are following functions
1. To discharge condensate as soon as it is formed
2. Not to allow steam to escape
3.To be capable of discharging air and other incondensable gases
Q13. Why boiler blow-down is required?
As the feed water evaporate into steam inside the boiler drum, dissolved solids concentrate in the boiler. Above undesirable limit of concentration, these solids encourage carryover of water into steam. This leads to scale formation inside the boiler, resulting in localized over heating and ending finally in tube failure. Hence blow-down is very much required for boilers.
Q14. Why steam condensate recovery is important in power plant ?
The condensate is very valuable not only because of its heat content but also because of its purity. It is already treated and any quantity of condensate recovered will also mean saving of treatment chemicals corresponding to that much of condensate.
Q15. Write a short note on IBR steam pipe.
IBR Steam Pipe means any pipe through which steam passes from a boiler to a prime mover or other user or both, when the pressure at which steam passes through such pipes exceeds 3.5 kg/cm2 above atmospheric pressure or such pipe exceeds 254 mm in internal diameter and includes in either case any connected fitting of a steam pipe.
Q16. What is water hammer in a steam system?
Water hammering is caused by condensate collect into the steam pipe line when we stop the boiler for long time period .A water hammer in a steam system is caused by condensate collection in the plant or pipe work picked up by the fast moving steam and carried along with it.
Q17. What is the affect of sulphur in coal when used in boiler?
Sulphur will get oxidized to SO2 and fraction of SO3 and will react with water to form sulphuric acid and this occurs at a temperature called the acid dew point which normally is about 120 oC. The sulphuric acid so formed corrodes the steel when it comes in contact with it.
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