Chapter 5 - Steam Power plant Flashcards
Total solid impurities in feed water for a boiler depend upon
Boiler Pressure
What is a high pressure chamber or a device in which the paths of rapidly moving particles can be observed and photographed?
Cloud Chamber
What is the formation of gas bubbles in a liquid called?
Foaming
How many check valves should be provided between any feed pump and boiler?
2
Water level inside the boiler is indicated by
Water column
What is the highest pressure under which distinguishable liquid and vapor phases can exist in equilibrium?
Critical Pressure
What is the average fuel – oil temperature range of the oil in the discharge line to the boiler?
180-200 °F
What is the lowest permissible water level of a boiler without internal furnace?
- 1/3 the height of the shell
In case of steam engine, the cut off ratio is the ratio of
- Friction of piston stroke which the piston has traveled when cut off occurs
In a condensing steam engine, what happens?
- Exhaust steam is condensed in a condenser
Flow through the nozzles and diffusers with increasing fluid velocity will create an equivalent
- Decrease in the static enthalpy of fluid
The term V^2 / 2Cp responds to the temperature during such a process and is called
- Dynamic temperature
All of the following mechanisms can supply heat to a thermodynamic system except
- Adiabatic expansion
The flow through the nozzle is
- Isentropic
If the reservoir is sufficiently large, the nozzle inlet velocity is
- Zero
What is the pressure applied at the nozzle discharge section?
Back Pressure
When the back pressure is reduced to the lowest exit pressure, the mass flow reaches a maximum value and the flow is said to be:
- Choked
Increase in stagnation pressure will increase the mass flux through the:
- Converging nozzle
A converging-diverging nozzle is the standard equipment in:
- Supersonic aircraft
For back pressure valves, abrupt changes in fluid properties occur in a very thin section of converging-diverging nozzle under supersonic flow condition, creating
- Shock wave
Locus of states which have the same value of stagnation enthalpy and mass flux are called:
- Fanno Line
Combination of mass and momentum equations into a single equation and plotted in h-s plane yield a curve called:
- Rayleigh Line
Generally steam turbines in power stations operate at:
- 3000 rpm
Which of the following shows the relationship of the steam consumption and the load of steam turbine generator?
- Willan’s line
An inventor proposes to develop electric power by withdrawing heat from the geyser fields of northern California and converting it all to work in power turbines. This scheme will not work because
- It violates 2nd law of thermo
The isentropic efficiency of a turbine is given by
- The ratio of actual to ideal energy extracted
Which of the following is not a main part of a typical coal burner?
- Atomizer
Measure of ability of a boiler to transfer the heat given by the furnace to the water and steam is:
- Boiler efficiency
A goose neck is installed in the line connecting a steam gauge to a boiler to:
- Protect the gauge element
Which of the following is a great advantage of a fire tube boiler?
- Contains a large volume of water and requires long interval of time to raise steam
One of the following tasks which is an example of preventive maintenance is
- Cleaning the cup on a rotary cup burner
The CO2 percentage in the flue gas of an efficiency fired boiler is approximately
- 12%
When droplets of water are carried by steam in the boiler, this is called
- Priming
The process in which heat energy is transferred to a thermal energy storage device is known as:
- Regeneration
When the boiler pressure increases or when the exhaust pressure decreases, the amount of moisture
- Increases
When the number of reheat stages in a reheat cycle is increased, the average temperature
- Increases
A heat transfer device that reduces a thermodynamic fluid from its vapor phase to its liquid phase such as in vapor compression refrigeration plant or in a condensing steam power plant is called
- Condenser
Simultaneous generation of electricity and steam in a single power plant is called
- Cogeneration
What is a liquid whose pressure is higher than the saturation pressure corresponding to its temperature?
- Compressed Liquid
In a steam generator with good combustion control, what occurs if the load is increased?
- Furnace Pressure is constant
Total solid impurities in feed water for a boiler depend upon
- Boiler Pressure
What is the gaseous state of water?
- Water vapor
A liquid boils when its vapor pressure equals
- The ambient pressure
What are the main components in a combined cycle power plant?
- Gas engine and waste heat boiler
A change in the efficiency of combustion in a boiler can usually be determined by comparing the previously recorded readings with the current readings of the
- Stack temp. and CO2
A boiler steam gauge should have a range of at least
- 1 and ½ times the maximum allowable working pressure
In a water tube boiler, heat and gases of combustion passed
- Around the tubes
What are the components in a combined cycle power plant?
Gas engine and waste heat boiler
How can a change in the efficiency of combustion in a boiler be determined?
By comparing the previously recorded readings with the current readings of the stack temp. and CO2
What should be the range of a boiler steam gauge?
At least 1 and ½ times the maximum allowable working pressure
In a water tube boiler, how do heat and gases of combustion pass?
Around the tubes
What is the chemical method of feedwater treatment that uses calcium hydroxide and sodium carbonate?
Lime soda treatment
How does the thermal efficiency of a gas-vapor cycle compare to that of a steam turbine or gas turbine?
Greater than
When does a rapid increase in boiler pressure occur?
When there is an abrupt drop in steam load
What is the most economical and low maintenance cost condenser?
Air-cooled
What is commonly done to the system when the turbine has excessive moisture?
Reheating
What is the result when the fluid’s kinetic energy during a stagnation process is transformed to enthalpy?
Rise in temp and pressure the fluid
How can the average temperature during the heat rejection process of a Rankine cycle be decreased?
By reducing turbine exit pressure
What ascertains the effectiveness and the size of a condenser?
Heat Transfer
If a boiler has a bursting pressure of 600kPa and a factor of safety of 8, would you advise a working pressure of 500 kPa?
No, WP is only 75 kPa at a FS of 8
What cycle is used in the vapor cycle of a steam power plant?
Rankine Cycle
What is the purpose of the gauge cock in the boiler?
To determine the level of water
