Heating surface to Boiler capacity

For many years five (5) square feet per boiler horsepower was the standard in the design of the traditional multi-pass fire tube boiler. In these cases about 40 - 50 % of the burner's heat energy was transferred in the furnace (first pass) as radiant energy, and the balance was transferred in the convection passes which consisted of 2 or 3 additional passes using 2 - 3" tubes some of which may have had turbulators to increase the heat transfer coefficient. Today, with the call for smaller fire tube footprints, and the use of sophisticated computer algoythms, i.e., Computational Fluid Dynamics (CFD) with Finite Element Analysis (FEA), boiler designers are able to produce smaller fire tube boilers with the same integrity and life as the old 5 square foot boiler; using a larger furnace (60-70% radiant heat absorbed), proper matching of burner to furnace, and extended surfaces in the convective tube passes which has now been reduced from 2 or 3 additional passes to 1. This not only preserves or enhances fuel to steam efficiency in a smaller package, but reduces the blower motor brake horsepower as well. A good example of the design is Cleaver Brooks CBEX Elite or Premium models which can be found on their website.

Copied from Linkedin.: Steve Connor, Director Marketing Services at Cleaver-Brooks

questions that need answers

Engineers faces the following questions when working factories and need answers:-
1. What is the pressure drop/back pressure developed in the burner in Hurst Boiler (300 series)?
2. What is ultimate pressure and significance in oil rotary pump ?
3. How the linear expansion of MS pipe can be measured ?
4.How the Chimney height is measured ?
5. What is COD and BOD in ETP and their significance?
6. What is single Point Lubrication?
7. What is RBD Oil and its uses?
8. What is torr , used in rotary oil pump and its equivalence unit?
9. What is the difference between bend and Elbow in pipe fittings and their applications?
 

written Exam Question for Mechanical Engineers

written Exam Question for Mechanical Engineers

1. Draw the stress-strain curve for Mild steel. Bangladesh Bank, Assistant Director (Mech.) -2013

2. What is modulus of Elasticity/Shear Stress? Bangladesh Bank, Assistant Director (Mech.) -2013

Answer:

Modulus of Rigidity/Shear Stress- within Elastic Limit, Ʈ ∞Ø, Ʈ = CØ , C= Ʈ/Ø,

Where C= Modulus of Rigidity, Ø= Shear Strain and Ʈ= Shear Stress

3. What is Modulus of Elasticity/young Modulus? Bangladesh Bank, Assistant Director (Mech.) -2013

Answer:

Modulus of Elasticity - within Elastic Limit, ð ∞€, ð =E. € , E= ð /€,

Where E= Modulus of Elasticity, ð = Stress and €= Strain

4. What is tonne of Refrigeration?  Bangladesh Bank, Assistant Director (Mech.) -2013

Answer:

Tonne of Refrigeration: The amount of refrigeration effect produced by uniform melting of one tonne (1000 Kg) of ice from and at 0^°C in 24 hours.

5. What is Jigs and Fixtures?  Bangladesh Bank, Assistant Director (Mech.) -2013

Answer:

Jigs: Jigs are used for holding and grinding the tool in drilling, reaming or taping operation

Fixtures: Fixtures are used for holding the work in milling, grinding, planning or turning operations.

GTCL exam questions 2010

GAS TRANSMISSION COMPANY LTD (GTCL) ASSISTANT ENGINEER WRITTEN TEST

GTCL is a government own company engaged in transmission of natural gas all over Bangladesh. Basis on the organogram total 664 officers and  257 staffs are working for GTCL. Honorable Senior Secretary, Energy and Mineral Resources Division Mr. Anisur Rahman,  is the GTCL board chairman. Upon vacancy  company management recruits Assistant Engineer (Electrical, Mechanical, Civil, Computer Science, Assistant Manager (General) as 1st class officer post for the grading scale 9, salary 22000-53060 (Bangladeshi Taka). For Assistant Engineer post required academic qualification is B.Sc. Engineering from a recognized university and for Assistant Manager (General ) post required academic qualification is Masters degree from a recognized university. No third Division is allowed to apply.   

1. Give Schematic diagram of GT. Cycle with regeneration and T-S diagram
2. In an IC Engine, bore X stroke is 250 mm X 300 mm, compression ratio is 10:1. Find out the combustion volume and displacement volume and total volume in CC.
3. For a pump suction head = 10 m, delivery head = 15 m, discharge = 10 m3/hr, Efficiency of the pump 0.9, now find out the power required.
4. Give T-S and P-V diagram of Brayton-Joule Cycle.
5. Give differences between Open and closed channel flow.
6. Give differences between the two stroke and four stroke cycle IC Engine.
7. What is the positive displacement pump. Give the examples.
8. In a thin walled cylinder, max. stress is given, ð= 50 M, diameter, d =100 mm, thickness, t=5 mm, find out the allowable pressure.
9. Give the example of gears, in where we use a worm gear.

If you will get know previous years question then you can take a good preparation. It is not easy to find these. I have collected many questions which will help future candidates for exam preparations. In academic life we used to appear in model test, test papers and solves the problems. But in professional life there is no such thing, specially for engineering job. A lots of questions are available:     EXAM QUESTIONS FOR ENGINEERING CATEGORY JOB

PDB Exam Questions

Bangladesh Power Development Board 

Recruitment Examination of Assistant Engineer -1999

Mechanical Engineering

Answer any six questions in English (Question No-1 is compulsory) 

1. a) what do you mean by Y2K problem? why this problem is being discussed throughout the world?

 b) What is meant by WHO, CTBT, SAARC, ME, MR, NATO, BPDB, SAPTA, UNO, SEATO,

c) Who is the secretary General of Common wealth summit? Where the common wealth was held in 1999?

d) Which team won the champion trophy in last world cup cricket final? Where the final match was held and who was the man of the match?

e) What do you mean by IPP? do you think that extensive privatization is the only way to active success in power sector? Give reason in support of your opinion.

f) Who won the novel prize from the sub continent in 1999? what was his subject ? name at least three persons also won the novel prize from the sub continent.

2. a) What is the differences between impulse and reaction Turbine?

b) Describe condenser of a steam turbine.

3. a) What is the advantages and disadvantages of two stroke and four stroke engine?

b) Draw the valve timing diagram of a four stroke cycle diesel engine.

4. a) What is acrofoil? Describe its operation with sketch.

b) What is Renolds number? What is its significant on the behavior of acrofoil?

5. a) Define fire tube and water tube boiler.

b) Compare between fire tube and water tube boiler.

6. a) What is refrigerant?

b) A refrigerant is rotated at 20 ton capacity, how many pounds of air per hour will it cool from 90 degree Fahrenheit to 70 degree Ferhenheit at constant pressure. What is the approximate engine horse power required to operate the plant?

(Assume COP=4 and CP=0.24)

7. a) Define Charles's law and Boyle's law.

b) Calculate the dia of a solid steel shaft to transmit a torque of 24,000 lb-ft with unit stress of 8000 psi.