Are you good at technical skills? Are you a trained craftsperson? Then boiler maker is the right job for you to enhance your skills. Wisdom jobs online portal will give you all the relevant information about the skills required for your job, training sessions and job related queries at one place. Log on to wisdom jobs online to get the overview of your job. A Boiler maker is a trained craftsman who produces steel fabrications from plates and tubes. Boiler makers assemble, install and repair boilers, closed vats and other large vessels or containers that hold liquids and gases. They perform physically demanding and dangerous works. So, to get appointed in a well reputed companies wisdom jobs experts have framed advanced boiler maker job interview questions and answers which will help you to get prepared for the interview successfully.
Question 1. What Is The Affect Of Sulfur In Coal When Used In Boiler?
Answer :
Sulfur will get oxidized to SO2 and fraction of SO3 and will react with water to form sulfuric acid and this occurs at a temperature called the acid dew point which normally is about 120 oC. The sulfuric acid so formed corrodes the steel when it comes in contact with it.
Question 2. What Do You Mean By Ibr Steam Boiler?
Answer :
IBR Steam Boilers means any closed vessel exceeding 22.75 liters in capacity and which is used expressively for generating steam under pressure and includes any mounting or other fitting attached to such vessel, which is wholly or partly under pressure when the steam is shut off.
Question 3. What Do You Understand By ‘water Tube Boilers’ And ‘fire Tube Boilers’?
Answer :
In water tube boilers the water passes through the tubes and the hot gases passes out side the tubes where as in case of fire tube boiler the hot gases passes through the tubes and the water passes over the tubes.
Question 4. What Is The Parameters Required To Estimate The Boiler Efficiency By ‘direct Method’?
Answer :
Question 5. Why Boiler Blow-down Is Required?
Answer :
As the feed water evaporate into steam, dissolved solids concentrate in the boiler. Above certain level of concentration, these solids encourage carryover of water into steam. This leads to scale formation inside the boiler, resulting in localized overheating and ending finally in tube failure. Hence blow-down is very much required for boilers.
Question 6. What Is The Principle Of Mechanical Deaeration (pressure Type) Of Boiler Feed Water?
Answer :
The 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.
Question 7. What Is The Effect Of Boiler Loading On Boiler Efficiency?
Answer :
Question 8. What Is The Principle Heat Losses That Occur In A Boiler?
Answer :
The principle heat losses that occur in a boiler are:
Question 9. What Does You Meant By Tangential Firing With Respect To Pulverized Coal Fired Boiler?
Answer :
The method of firing used for coal firing in pulverized fuel fired boiler is the tangential firing. In this type of firing four burners are used at the corner to corner to create a fire ball at the center of the furnace.
Answer :
Direct method:
Answer :
The data required for calculation of boiler efficiency using indirect method are:
Question 12. Explain The Different External Water Treatment Methods?
Answer :
Question 13. What Are The Salient Features Of A ‘packaged Boiler’?
Answer :
The features of package boilers are:
Question 14. What Are The Two Main Classification Of A Stoker Fired Boiler?
Answer :
Question 15. Briefly Explain The Principle Involved In ‘reverse Osmosis’?
Answer :
Question 16. What Are The Various Methods Available To Control The ‘excess Air’ In A Boiler?
Answer :
Various methods are available to control the excess air:
Question 17. Describe ‘chain Grate’ And ‘spreader Stoker’ Type Boiler?
Answer :
Chain-Grate or Travelling-Grate Stoker Boiler:
Coal is fed onto one end of a moving steel grate. As grate moves along the length of the furnace, the coal burns before dropping off at the end as ash. Some degree of skill is required.
particularly when setting up the grate, air dampers and baffles, to ensure clean combustion leaving the minimum of unburnt carbon in the ash. The coal-feed hopper runs along the entire coal-feed end of the furnace. A coal grate is used to control the rate at which coal is fed into the furnace by controlling the thickness of the fuel bed. Coal must be uniform in size as large lumps will not burn out completely by the time they reach the end of the grate.
Spreader Stoker Boiler:
Spreader stokers utilize a combination of suspension burning and grate burning. The coal is continually fed into the furnace above a burning bed of coal. The coal fines are burned in suspension; the larger particles fall to the grate, where they are burned in a thin, fast-burning coal bed. This method of firing provides good flexibility to meet load fluctuations, since ignition is almost instantaneous when firing rate is increased. Hence, the spreader stoker is favored over other types of stokers in many industrial applications.
Answer :
The ‘intermittent blown down’ is given by manually operating a valve fitted to discharge pipe at the lowest point of boiler shell to reduce parameters (TDS or conductivity, pH, Silica and Phosphates concentration) within prescribed limits so that steam quality is not likely to be affected. In intermittent blow down, a large diameter line is opened for a short period of time, the time being based on a thumb rule such as “once a shift for 2 minutes”. ‘Intermittent blow down’ requires large short-term increases in the amount of feed water put into the boiler, and hence may necessitate larger feed water pumps than if continuous blow down is used. Also, TDS level will be varying, thereby causing fluctuations of the water level in the boiler due to changes in steam bubble size and distribution which accompany changes in concentration of solids. Also substantial amount of heat energy is lost with intermittent blow down.
‘Continuous Blowdown’:
There is a steady and constant dispatch of small stream of concentrated boiler water, and replacement by steady and constant inflow of feed water. This ensures constant TDS and steam purity at given steam load. Once blow down valve is set for a given conditions, there is no need for regular operator intervention. Even though large quantities of heat are wasted, opportunity exits for recovering this heat by blowing into a flash tank and generating flash steam. This flash steam can be used for pre-heating boiler feed water or for any other purpose. This type of blow down is common in high-pressure boilers.
Question 19. Explain The Reasons For Carrying Out “blow Down” In A Boiler?
Answer :
Water contains certain percentage of dissolved solids. The percentage of impurities found in boiler water depends on the untreated feed water quality, the treatment process used and the boiler operating procedures. As a general rule, the higher the boiler operates pressure, the greater will be the sensitivity to impurities. As the feed water materials evaporate into steam, dissolved solids concentrate in the boiler either in a dissolved or suspended state. Above a certain level of concentration, these solids encourage foaming and cause carryover of water into the steam. This leads to scale formation inside the boiler, resulting in localized overheating and ending finally in tube failure. It is therefore necessary to control the level of concentration of the solids and this is achieved by the process of ‘blowing down’, where a certain volume of water is blown off and is automatically replaced by feed water – thus maintaining the optimum level of total dissolved solids (TDS) in the water. Blow down is necessary to protect the surfaces of the heat exchanger in the boiler.
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