Chapter 16 ( Machine Foundation & Chimney ) Flashcards
Foundation are preferably built of concrete in the proportion of what measure of Portland cement: sand : crushee stones?
1 : 2 : 4
For design stability, the center of gravity of the total combined engine, drive equipment and foundation should be kept ______
below the foundation top
The machine foundation must have a factor safety of ___
5
Diesel engine foundation safe soil bearing pressure is:
4,890 kg/cm²
Anchor bolts in a machine foundation should
30
As a good practical rule, the foundation depth may be taken as how many times of the engine stroke?
3.2 to 4.2
To secure the belts embedded within the foundation, the distance of the edges of the foundation from the bedplate must be ______
120 mm to 300mm
Weight of the machine foundation is how many time the weight of the engine
3 to 5 times
To eliminate transmission of vibration, the foundation should be isolated from floor slabs or building footings at least how many mm around its perimeter?
25 mm
Minimum vertical distance from the floor to the top edge of foundation
120 mm
There shall be no foundation bolts less than ____
12 mm in diameter
Weight of steel bar reinforcements should be how many times the weight of the foundation
1/2 % to 1%
Concrete foundation should have steel bar reinforcements placed vertically and horizontally to avoid _____
Thermal Cracking
Foundations bolt length should be at least how many times the anchor bolt diameter?
18 times
Foundation bolts of specified size should be used and surrounded by a pipe sleeve with an inside diameter of at least how many times the diameter of the anchor bolt?
3
For a diesel engine’s foundation, in pouring a concrete mixture, it should be poured:
one time
For foundations of steam turbine, the concrete mixture should be ____
1 : 2 : 4
The steam turbine foundation should be designed to support the machine load plus how many percent for impact, condenser loaf, floor loads and dead loads?
25 %
Which of the following draft rely on the stack effect to draw off combustion gases?
Natural Draft
Fans located before the furnace that are used to supply air for burning.
Forced Draft
Forced draft fans run at relatively high speeds in what range:
1200 - 1800 RPM
Chimneys that rely on natural draft are referred as:
Gravity Chimney
Force draft fans create a positive pressure of:
0.5 to 2.5 kPa
Fans that are used to draw combustion products through the furnace bed, stack and pollution control system injecting air into the stack after combustion
Induced Draft
The term used when the static pressure is equal to the atmospheric pressure
Balanced Draft
In order to keep combustion products inside the combustion chamber and stack system, balanced draft system may actually operate with a slight _____
negative pressure
the static pressure drop due to friction through the boiler
draft loss
The difference between the theoretical draft and the draft loss
Available draft
In a balanced system, the available draft is _____
Zero
The total pressure supplied by the fan at maximum operating conditions
net rating or fan boost
Generally, The higher the chimney, the ______
the greater the stack effect
Modern stacks are seldom built higher than ____
60 m
Most stacks are built of height less than _____
30 m
The average flue gas temperature is_____
the temperature halfway up the stack
Coefficient of velocity is approximately:
0.30 to 0.50
For realistic problems, the achievable stack effect probably should be considered to be:
80% of the ideal
Guyed stacks seldom exceed:
1.83 m in diameter
The angle between the stack and the guy wire is :
60 degrees
Guyed stacks HEIGHT seldom exceed:
30.48 m
Maximum unit pressure of turbine and generator on the reinforced concrete
17.62 kg/cm²
In guyed steel stacks, the angle between wires in a set of three is:
120 degrees
Guys are usually applied in how many sets ?
1 to 3
The empirical coefficient (e) in machine foundation if not given is ____
0.11
The term suction units is used with
Induced Draft
