An economiser in a boiler
Increases steam pressure
Increases steam flow
Decreases fuel consumption
Decreases steam pressure
Correct Answer :
C. Decreases fuel consumption
Related Questions
A safety valve mainly used with locomotive and marine boilers is
Lever safety valve
Dead weight safety valve
High steam and low water safety valve
Spring loaded safety valve
Willian's law states that the steam consumption per hour provided with a throttled governor is proportional to (where I.P. = Indicated power)
1/(I.P)
1/(I.P)²
I.P.
(I.P.)²
Latent heat of dry steam at atmospheric pressure is equal to
539 kcal/ kg
539 BTU/ lb
427 kcal/ kg
100 kcal/ kg
The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle)
Vb = 0.5 V cosα
Vb = V cosα
Vb = 0.5 V² cosα
Vb = V² cosα
Which of the following statement is correct?
A fire tube boiler occupies less space than a water tube boiler, for a given power.
Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.
A simple vertical boiler has one fire tube.
All of the above
In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the atmospheric pressure.
Equal to
Lower than
Higher than
None of these
When the speed of the crankshaft is between 100 r.p.m. and 250 r.p.m., the engine said to be a
Slow speed engine
Medium speed steam engine
High speed steam engine
None of these
The function of a crosshead is to guide motion of the _________ and to prevent it from bending.
Piston rod
Connecting rod
Eccentric rod
Valve rod
The ratio of the isentropic heat drop to the heat supplied, is called
Reheat factor
Stage efficiency
Internal efficiency
Rankine efficiency
The artificial draught is produced by
Steam jet
Centrifugal fan
Chimney
Both (A) and (B)
In a uniflow engine
Steam enters and exhausts through the same port
Steam enters at one end and exhausts at the centre
Steam enters at the centre and exhausts at the other end
None of the above
Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of
Higher effectiveness of boiler
High calorific value coal being burnt
Fouling of heat transfer surfaces
Raising of steam temperature
The equivalent evaporation is defined as
The ratio of heat actually used in producing the steam to the heat liberated in the furnace
The amount of water evaporated or steam produced in kg per kg of fuel burnt
The amount of water evaporated from and at 100°C into dry and saturated steam
The evaporation of 15.653 kg of water per hour from and at 100°C
An economiser _________ the steam raising capacity of a boiler.
Increases
Decreases
Has no effect on
None of these
The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)
ηS = ηB × ηN
ηS = ηB / ηN
ηS = ηN / ηB
None of these
The compounding of turbines is done in order to
Reduce speed of rotor
Improve efficiency
Reduce exit losses
All of these
Pick up the wrong statement about water tube boiler in comparison to fire tube boilers
Former occupies less space for same power
Rate of steam flow is more in former case
Former is used for high installed capacity
Chances of explosion are less in former case.
The ratio of total useful heat drop to the total isentropic heat drop, is called
Stage efficiency
Internal efficiency
Rankine efficiency
None of these
Which of the following is steam dial?
Non-coking bituminous coal
Brown coal
Pulverised coal
Coking bituminous coal
The average value of diagram factor lies between
0.2 to 0.5
0.5 to 0.65
0.65 to 0.9
0.8 to 1.2
The variation of steam pressure in the nozzle depends upon
Velocity of steam
Specific volume of steam
Dryness fraction of steam
All of these
The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)
sin²α
cos²α
tan²α
cot²α
The critical pressure ratio (p₂/p₁) is given by
(p₂/p₁) = [2/(n - 1)] n/(n + 1)
(p₂/p₁) = [2/(n + 1)] n/(n-1)
(p₂/p₁) = [(n - 1)/2] n + (1/n)
(p₂/p₁) = [(n + 1)/2] n - (1/n)
In an impulse turbine
The steam is expanded in nozzles only and there is a pressure drop and heat drop
The steam is expanded both in fixed and moving blades continuously
The steam is expanded in moving blades only
The pressure and temperature of steam remains constant
A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
Back pressure turbine
Pass out turbine
Low pressure turbine
Impulse turbine
The critical pressure ratio for initially dry saturated steam is
0.546
0.577
0.582
0.601
Degree of reaction is defined as the ratio of
Heat drop in fixed blades to the heat drop in moving blades
Heat drop in moving blades to the heat drop in fixed blades
Heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
Heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades
Expanding steam to a very low pressure (high vacuum) in steam engines is
Desirable
Economical
Essential
Uneconomical
The discharge is __________ at critical pressure.
Zero
Minimum
Maximum
None of these
If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
ps - pa
pa - ps
pa + ps
None of these