Heii all my Askpowerplant.com users today we discussed a very important topic which is related to BOE examination so that it’s topic is very essential for those we want to prepared for boe examination and also for those who preparing for the interview for Boiler first-class or power plant shift in charges as well boe viva vice preparation. so please read this article up to the end if you liked this article please share. in this article, we discussed MAHARASHTRA BOE EXAM PAPER – 2012 Question & Answers paper-1 in this exam board asking 10 questions which is one marks if candidate giving the answers all these questions correctly then he awarded 10 out 10 so if we are looking into getting good marks in BOE exam then these question answers importance increases. so lets discussed MAHARASHTRA BOE EXAM PAPER – 2012 Question & Answers paper-1
Q 1. Deaerator is placed at higher elevation
a.) For good housekeeping
b.) To keep the building cool
c.) To increases NPSH and avoid cavitation in boiler feed pump
d.) To vent steam easily
Hint: Deaerator in steam turbine plants/Power Plants always installed at heights because of it’s two main reasons which we discussed here one of them is to increases NPSH (Net positive suction head ) and the second one is for avoiding cavitation in the boiler feed pump when the boiler feed pump is in operation, low pressure is created at the suction end of the pump, there is a chance of steaming of feed-water, as water is at a higher temperature. this is called cavitation whenever pressure at the suction side of the boiler feed pump drop below saturated pressure, this situation may arise. to avoid this situation, the Deaerator is placed at a higher level. if the Deaerator pressure is 2kg/cm2 and the Deaerator is placed at an elevation of 20meter, then the pump suction pressure will be approximately 5 kg/cm2.
Q 2. Stoichiometric combustible mixture speaks about
a.) Fuel calorific value
b.) Temperature of air and fuel
c.) Unburnt carbon in flue gas
Hint: The Stoichiometric ratio is the calculated amount of ratio in between air and flammable gas or vapour at which complete combustion take place . the Stoichiometric ratio combustion varies for different fuels and oxidizer . A Stoichiometric ratio is neither too rich( more ) nor too lean (less ) . it contains just enough oxygen to burn all the fuel .
In the Theoretical air is the minimum amount of air-fuel ratio in which complete combustion of the fuel take place is called the theoretical air .
Q 3. As per Indian Boiler, rule section-392, major repair such as fusion weld is to be entrusted to a repairer
a.) Who can satisfy owner regarding quality of welding
b.) Who can satisfy the boiler director regarding quality of welding
c.) Who can satisfy the manager regarding quality of welding
d.) Who has qualified welder with him
Hint: As per Indian Boiler, rule section-392, major repair such as fusion weld is to be entrusted to a repairer who can satisfy owner regarding quality of welding .
According to boiler act Reg. 392, following consideration made
Repairs to boilers and steam pipes :
In Major repairs of boilers such as fusion welded or riveted patches to shells, fire boxes and end plates of boilers and extensive building up of wasted parts of boilers permitted under these regulations, the renewal of furnaces and end plates, parts of shell, fire boxes, girders and steam-pipes, etc. shall only be entrusted to a firm who is recognized as a repairer under these regulations.
Q 4. Pressure drop across which type valve is more
a.) Gate valve
b.) Butterfly valve
c.) Globe valve
d.) Plug valve
Hint: Pressure drops across globe valve as compare to gate valve because a globe valve changes the direction of flow and the seat opening is almost always smaller than the pipe diameter so it presents measurable friction loss.
Q 5. Safety valve is installed at low pressure side of pressure reducing station to
a.) Releases over pressure due to failure of control valve
b.) Releases steam to maintained pressure
c.) open during high temperature
d.) Open during high moisture
Hint: Safety valve is installed at low pressure side of pressure reducing station to Releases over pressure due to failure of control valve . Safety valves are the main important part of the steam PRV ( Pressure Reducing Valve ) station. But they may not be required in every case. Whenever steam component or the steam line downstream of the steam PRV( Pressure Reducing Valve ) is not rated for the maximum inlet steam pressure to the PRV station, then a safety valve must be installed to protect the system.
For the maximum steam flow the safety valve needs to be sized with respect to the highest steam pressure that could be provided to the PRV. In addition, to rectified the proper safety valve size should be performed , on the basis of calculations with the largest Cv trim available for the PRV. During the installing of a safety valve, we should insured the discharge is piped to a location where it will not generate any safety risk for plant or personnel.
Q 6. Bed slumping is done in AFBC boiler to
a.) Reduced pressure
b.) Reduced temperature
c.) Reduced Load
d.) Maintained Bed Temperature
Hint: Total bed of FBC boiler is divided into compartments each compartments is having independent coal feeding system with it’s own air box and air nozzles for fluidisation . depending upon the load on the boiler on the boiler some compartments are taken out of services . This procedure is called compartments slumping and bed slumping . so Bed slumping is done in AFBC boiler to reduced Load . so that Bed slumping is done in AFBC boiler to reduced Load.
Q 7. Mobrey switch is used to
a.) Control drum level
b.) control fuel flow
c.) Control air flow
d.) Maintained fan speed
Hint: According it’s name Mobrey used for the Automatic water level controller-or automatic water maintaining , it comes under the category of mountings and fittings of Steam Boiler Assembly. Mobrey is used for maintaining the water level in the Boiler shell. It is mostly used in smoke tube steam boilers not in water tube boilers so that Mobrey switch is used to control drum level .
Q 8 . Scoop tube control is used in feed pump to
a.) Control vibration
b.) Current Measurement
c.) control Ph of feed water
d.) control drum level
Hint: Generally Boiler Feed pump motor always ruining with constant speed during in star-delta mode but with the help of scoop tube system , the RPM of the pump varied . input to the scoop tube system is the differential pressure (DP) across the boiler feed water regulating system control valve ( In turn , drum level , 3 or 1 – element controller will maintain the feed water station control valve position so that scoop tube control is used in feed pump to control the drum level .
Q 9. For easy storage of bagasse
a.) Bagasse is air drayed
b.) Balling is done
c.) Bagasse is washed
d.) Water is sprayed
Hint:when the sugarcane crushing happening in the sugar industry after cane crushing with the help of steaming we removed all the juice from the sugar cane after removing it crushed cane goes through big rollers where remaining moisture removed out after that when high moisture content remains bagasse, typically 40–50 percent, is detrimental to its use as a fuel. In general, bagasse is stored prior to further uses for other purpose For electricity production, it is stored under moisture conditions, and the mild exothermic process that results from the degradation of residual sugars dries the bagasse pile slightly For easy storage of bagasse , bagasses should be is air drayed
Q10 . Oil burner is used in Pulverize boiler to
a.) To reduced soot formation
b.) To reduced coal consumption
c.) Stabilize the flame during low load and provide ignition energy during start-up
d.) To increase reheat steam temperature
Hint: Oil burner is used in Pulverize boiler to Stabilize the flame during low load and provide ignition energy during start-up
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